Year 7 Science Homework Pack Student Name:
Student Name: Year 7 Science Homework Pack Forces Due in Friday 25th April 2014
The options that I have completed for my Home Learning are (Please tick): Option Number
Vivomiles
Forces are everywhere
3 Vivomiles
Forces circus
5 Vivomiles
Measuring forces
3 Vivomiles
Find the forces
3 Vivomiles
Which way?
5 Vivomiles
Balanced or unbalances?
5 Vivomiles
That floating feeling
7 Vivomiles
Upthrust in different liquids
5 Vivomiles
Floating questions
10 Vivomiles
Archimedes
10 Vivomiles
Stretching springs
5 Vivomiles
Rope climbing
5 Vivomiles
True or false?
5 Vivomiles
Friction Around us & What’s rubbing?
10 Vivomiles
Speed check & Need for speed
15 Vivomiles
Completed?
What do I need to do? In Science you are currently studying Forces. In this module you will be learning about forces in action, balanced and unbalanced forces, calculating speed, density and pressure. To support the work that you are doing in science, all of the home learning activities below will help you to further your understanding of forces. Check which teaching group you belong to and start to work out which home learning activities you have to select from. If you are not sure – Ask for help! Teaching Group
What do I need to do?
7R1
Select home learning activities that total a minimum of 50 Vivomiles* Select home learning activities that total a minimum of 35 Vivomiles* Select home learning activities that total a minimum of 25 Vivomiles*
7C1 7S1
* Remember that there is nothing stopping you from completing more home learning activities for more Vivomiles!
Forces and their effects In this topic you will learn: About force and its measurement
About friction, air resistance and upthrust
About mass and weight
About speed and change in motion
About balanced and unbalanced forces
Lesson 1– what can forces do?
Which forces are pushes and which are pulls? Write the correct word in the spaces.
_________________
_________________
_________________
_________________
For the pictures below, write the name of the force acting on the object. A
B
C
_____________ D
_____________ E
_____________ F
_____________
_____________
_____________
In the space below describe what forces can do to objects. (think about some of the forces you have used today). …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… ……………………………………………................................................................................. 1
Look at these 6 experiments looking at forces. Fill in the missing words below each experiment.
The magnets are ________________ (attracting/repelling) each other. The force is strongest when the magnets are ______________ (close together/far apart). The name of this force is _____________ (friction/gravity/magnetism).
The force of _______________ (friction/ gravity/magnetism) tries to stop the blocks moving across the desk. It is ________________ (easier/harder) to push the block of ice, because the ice is________________ (smoother/rougher).
It is ________________ (harder/easier) to tie a knot in the plastic string. The plastic string has a _________________ (rough/smooth) surface so there is less _____________ (friction/gravity/magnetism).
2
The force from the spring gets ______________ (bigger/smaller) if it is stretched further. The spring is _____________________ (pulling/pushing)
Weigh the object. How much does your object weigh? _______________ The force of ____________________ (friction/ gravity/magnetism) is pulling the object downwards.
The paper takes ________________ (less time/more time) to fall if it is crumpled up. The air resistance is _______________ (more/less) when the paper is crumpled up.
Can you describe any other experiments that you could carry out to test the effects of forces?............................................................................ …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………... 3
Newtonmeters are used to measure how big a push or pull is. Since pushes and pulls are forces a newtonmeter is actually measuring the size of the force. Forces are always measured in newtons. Write down the force each of these newtonmeters is measuring.
Force =……………..N Force =……………..N Force =……………..N Which of the forces is the largest?..........................N Which of the forces is the smallest?........................N Both of the meters measure forces in newtons. Circle the one that measures the force of gravity on your body. What do you think the main part of each meter is?................................
4
Write the answers to the clues in the spaces. Clues
Answers
a
A force which pulls you down.
______________
b
This force helps to hold things to fridge doors.
______________
c
This type of force needs to touch something to affect it. ______________
d
This force rubs things away.
______________
e
This force helps a ship float.
______________
f
A form of electricity which can attract things.
______________
Now try to find the words in the wordsearch. Mark all the contact forces in red and the non-contact forces in blue. (Use pen and pencil if you do not have any coloured pencils.) W
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Homework sheet
Name………………………………………...
Mark the diagrams with arrows to show the forces. Most of the pictures have more than one force. Write in the name of each force. Think about whether the forces are balanced or not. When you draw arrows to show balanced forces, both arrows should be the same size. If the forces are unbalanced, the biggest force should have the biggest arrow. The first one has been done for you.
5
Lesson 2– what forces act on objects that float and sink
Describe the movement of the boat in the pictures below, use the words balanced and unbalanced in your answer.
…………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… ………………................................................................................................ ................................................................................................................ ................................................................................................................ ................................................................................................................ ................................................................................................................ 6
Is there a connection between an objects density and whether it floats or sinks? Density is a measure of how much mass there is in 1 cm3 of something. Density depends on the mass of an object and its volume. You will measure a range of objects and work out the density of each. You will then test to see if each object floats or sinks.
Density=
Material
Mass (g)
Length (cm)
Height (cm)
Width (cm)
mass volume
Volume (cm3)
Density Floats 3 (g/cm ) or sinks?
Write a conclusion for this experiment……………………………………………………. …………………………………………………………………………………………………………………………… 7
You are going to find out if the amount of upthrust depends on the liquid. Even objects that sink have upthrust acting on them, but the upthrust is not big enough to make them float. You can measure upthrust by finding out how much the weight of an object changes when you put it in water. We can work out the upthrust of a liquid using the following equation: Upthrust = weight in air – weight in liquid
Your teacher will give you a sample of some different liquids, you will find out the upthrust of each liquid using the information above. You can work out the density of liquids by measuring out equal volumes and finding their mass. (remember density= mass/volume) After your experiment answer the following questions.: Does the upthrust depend on the kind of liquid?....................................... …………………………………………………………………………………………………………………………… What is the connection between the density of the liquid and the amount of upthrust it provides?.................................................................... …………………………………………………………………………………………………………………………… 8
Josh was in the sea at high tide when he came across a large stone under the water. He tried to lift the stone and was surprised to find that he could move it easily. He returned at low tide and found the stone out of the water. This time he could hardly move it.
The stone felt lighter when it was under ________________ . This is because ________________ was helping to push it up. The stone does not float because its ________________ is greater than the ________________ . The two forces which affect the stone are ________________ and ________________ . This is Danny floating in the water. Label the two forces.
Your weight is 600 N and you have just finished building a raft which weighs 1000 N. What is the total weight of you and the raft? ________________ What is the smallest upthrust force needed so that it will just float with you on it._______________________________________________________
9
Homework sheet
Name…………………………………………………….. Group……………
Archimedes lived in Syracuse, Italy, and was a great inventor and philosopher. One of the scientific facts that he discovered is called Archimedes’ Principle. The upthrust on something in a fluid is equal to the weight of fluid displaced. 1
2
a
What is the weight of the stone?......................................................................................
b
What is the upthrust on the stone when it is in the water?.......................................
c
What is the weight of the water in the small beaker?.................................................
d
Why doesn’t the stone float?..............................................................................................
If you compared the weight of the stone in air with its weight in water, the
difference would be the weight of the water displaced by the stone. This difference is the upthrust. a
What is the weight of the wooden block?........................................................................
b
What is the upthrust on the block?...................................................................................
c
What is the weight of the water in the small beaker?.................................................
d
Why does the wooden block float?....................................................................................
3
All the beakers have water in them.
a Which object is the heaviest?................................. How do you know?............................... ………………………………………………………………………………………………………………………………………………………………… b
Write the three objects in order of their weight, starting with the heaviest…………..
………………………………………………………………………………………………………………………………………………………………... Explain how you worked out your answer………………………………………………………………………………………. 4
a
What would happen if you put a 1 N weight on top of block Z?................................
………………………………………………………………………………………………………………………………………………………………... b
What would the extra water in the small beaker weigh?...........................................
……………………………………………………………………………………………………………………………………………………….. 5
Some of the things Archimedes invented are still in use today. Find out what an ‘Archimedes screw’ is and what it is used for……………………………………………………………………..
………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………………...
Lesson 2– what can forces act on a spring?
List some of the uses of springs in the space below.
You are going to investigate the forces that act on springs. First take a spring and push it down against the table and stretch it gently in your hands. Describe what you can feel and what happens to the spring……………………………………………………………………………………………………. …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… How is a spring stretched by different forces? You will set up a clamp, spring and ruler as shown in the diagram. You will hang different weights from the spring and measure how far the spring stretches. Record your results in a table in the space below.
Write a conclusion for your experiment here…………………………………………. …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… 10
Rock climbers and mountaineers use ropes to stop them getting hurt if they fall, but did you know that climbing ropes are stretchy?
Think about a spring like this chest expander. It is quite easy to stretch it a little way, but it takes a much bigger force to stretch it a long way. The amount of force from the spring depends on how far it has been stretched. The same thing happens with climbing ropes.
1
Label the force or forces acting on the falling climber in picture B?
2
a
Label the forces acting on the climber in C?
b
Are the forces balanced or unbalanced?..................................................................
c
What will happen to the falling speed of the climber?.........................................
3
Are the forces balanced or unbalanced in D? Balanced forces do not change the speed of something that is moving…………………………………………………………………………………...
4
a Will the climber fall further than the point she has already reached in D? Explain your answer…………………………………………………………………………………………………………….. b
What will happen to the force from the rope if she falls further? What effect will this have on her speed?............................................................................
…………………………………………………………………………………………………………………………………………………. 5
a If she had a stretchier rope than the one shown, would she fall further or not as far? What would happen if the rope was too stretchy? 11
The statements below are all about friction. Some are true, some are false, and some are partly true. Colour in the boxes at the top with a different colour then colour in the statements saying if they are true, partly true or false.
True
False
Partly true
Friction always slows things down.
Cars need friction to keep moving.
Cars need friction to stop.
You could not walk without friction.
Friction is useful to gymnasts.
Matches light because of friction.
Friction is useful to ships.
Shoelaces stay tied up because of friction.
You could not pick up a cup of tea without friction.
You could drink from a glass without friction.
Snow increases the friction between your shoes and the ground.
Friction is useful in playgrounds.
Pencils do not need friction to write.
There is no friction when you are rollerskating.
Imagine a world without friction. Try and describe some of the things you would and wouldn’t be able to do……………………………………………………………………………. ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………......... ........................................................................................................................................... ........................................................................................................................................... 13
Lesson 5– what is friction and what can it do?
Copy the sentences and fill in the missing words. The words you need are in the box. Force
Rough
Smooth
Surfaces
Friction is a ___________________ caused by two __________________ moving over each other. ___________________ surfaces produce more friction than _________________ surfaces. Look at these diagrams. Put a circle around the all the places where there is friction. One has been done for you.
3
Look at these pictures.
You pull the block along all of these surfaces.
It will be easiest to pull the block along the ___________________ . This is because it has the ___________________ (smoothest/roughest) surface, so there will be the ___________________ (most/least) friction. It will be hardest to pull the block along the ___________________. This is because it has the ___________________ (smoothest/roughest) surface, so there will be the ___________________ (most/least) friction. 14
Homework sheet
Name………………………………………………
Fill in the gaps in these sentences. Friction is a ____________ caused by two ____________ moving over each other. ____________ surfaces produce more friction than ____________ surfaces. Friction can be helpful, because it stops us ____________ when we walk, and ____________ that slow down cars or bicycles could not work without friction. Friction is not always useful. It can cause ____________ and ____________ , and ____________ away things that rub against each other. Oil can reduce the amount of ____________. Oil stops the surfaces touching each other. Liquids that reduce friction are called ____________ . Look carefully at these pictures.
On the other side of this sheet, for each picture: a
Describe where there is friction.
b
Say whether the friction is helpful or unhelpful.
c
Describe how the friction could be increased or decreased.
Can you match up the pictures to the speed they would move at?
37 km/h
240 km/h
6 km/h
8 cm/minute
750 km/h
25 cm/year
A car going at 30 mph covers 30 miles in each hour. Write out in words what the following figures mean: a
60 mph
____________________________________________
b
20 km/h ____________________________________________
c
40 m/s
____________________________________________
Look at the pictures again. a
The force that stops the racing car from skidding is called ______________________ .
b
Two forces are trying to make the racing car slow down. They are ______________________ and _____________________ ______________________ .
15
To work out a speed you have to know a distance and a time. You can calculate the speed using this formula: speed = distance/time Sometimes we know the speed of something, and we want to find out how far it will go in a certain time, or how long it will take to get somewhere. The formula can be arranged like this: distance = speed x time or time = distance/speed
1
The car on the motorway can travel 1860 metres in 60 seconds. Work out how fast the car is going. Don’t forget the units!
2
The dog runs 1980 metres in 5 minutes. How fast is he running? (Hint: Remember, there are 60 seconds in each minute.)
3
a
How far will the girl cycle in 1 hour? (Hint: 1 hour = 3600 seconds)
b
How far will the train go in 60 seconds?
c
How far will the cockroach run in 10 seconds?
4
How long will it take for the girl to cycle 4 km?
5
a
How many metres will the train travel in 1 hour?
b
How far is this in kilometres? 17
The options that I have completed for my Home Learning are (Please tick): Option Number
Vivomiles
Forces are everywhere
3 Vivomiles
Forces circus
5 Vivomiles
Measuring forces
3 Vivomiles
Find the forces
3 Vivomiles
Which way?
5 Vivomiles
Balanced or unbalances?
5 Vivomiles
That floating feeling
7 Vivomiles
Upthrust in different liquids
5 Vivomiles
Floating questions
10 Vivomiles
Archimedes
10 Vivomiles
Stretching springs
5 Vivomiles
Rope climbing
5 Vivomiles
True or false?
5 Vivomiles
Friction Around us & What’s rubbing?
10 Vivomiles
Speed check & Need for speed
15 Vivomiles
Completed?
What do I need to do? In Science you are currently studying Forces. In this module you will be learning about forces in action, balanced and unbalanced forces, calculating speed, density and pressure. To support the work that you are doing in science, all of the home learning activities below will help you to further your understanding of forces. Check which teaching group you belong to and start to work out which home learning activities you have to select from. If you are not sure – Ask for help! Teaching Group
What do I need to do?
7R1
Select home learning activities that total a minimum of 50 Vivomiles* Select home learning activities that total a minimum of 35 Vivomiles* Select home learning activities that total a minimum of 25 Vivomiles*
7C1 7S1
* Remember that there is nothing stopping you from completing more home learning activities for more Vivomiles!
Forces and their effects In this topic you will learn: About force and its measurement
About friction, air resistance and upthrust
About mass and weight
About speed and change in motion
About balanced and unbalanced forces
Lesson 1– what can forces do?
Which forces are pushes and which are pulls? Write the correct word in the spaces.
_________________
_________________
_________________
_________________
For the pictures below, write the name of the force acting on the object. A
B
C
_____________ D
_____________ E
_____________ F
_____________
_____________
_____________
In the space below describe what forces can do to objects. (think about some of the forces you have used today). …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… ……………………………………………................................................................................. 1
Look at these 6 experiments looking at forces. Fill in the missing words below each experiment.
The magnets are ________________ (attracting/repelling) each other. The force is strongest when the magnets are ______________ (close together/far apart). The name of this force is _____________ (friction/gravity/magnetism).
The force of _______________ (friction/ gravity/magnetism) tries to stop the blocks moving across the desk. It is ________________ (easier/harder) to push the block of ice, because the ice is________________ (smoother/rougher).
It is ________________ (harder/easier) to tie a knot in the plastic string. The plastic string has a _________________ (rough/smooth) surface so there is less _____________ (friction/gravity/magnetism).
2
The force from the spring gets ______________ (bigger/smaller) if it is stretched further. The spring is _____________________ (pulling/pushing)
Weigh the object. How much does your object weigh? _______________ The force of ____________________ (friction/ gravity/magnetism) is pulling the object downwards.
The paper takes ________________ (less time/more time) to fall if it is crumpled up. The air resistance is _______________ (more/less) when the paper is crumpled up.
Can you describe any other experiments that you could carry out to test the effects of forces?............................................................................ …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………... 3
Newtonmeters are used to measure how big a push or pull is. Since pushes and pulls are forces a newtonmeter is actually measuring the size of the force. Forces are always measured in newtons. Write down the force each of these newtonmeters is measuring.
Force =……………..N Force =……………..N Force =……………..N Which of the forces is the largest?..........................N Which of the forces is the smallest?........................N Both of the meters measure forces in newtons. Circle the one that measures the force of gravity on your body. What do you think the main part of each meter is?................................
4
Write the answers to the clues in the spaces. Clues
Answers
a
A force which pulls you down.
______________
b
This force helps to hold things to fridge doors.
______________
c
This type of force needs to touch something to affect it. ______________
d
This force rubs things away.
______________
e
This force helps a ship float.
______________
f
A form of electricity which can attract things.
______________
Now try to find the words in the wordsearch. Mark all the contact forces in red and the non-contact forces in blue. (Use pen and pencil if you do not have any coloured pencils.) W
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Homework sheet
Name………………………………………...
Mark the diagrams with arrows to show the forces. Most of the pictures have more than one force. Write in the name of each force. Think about whether the forces are balanced or not. When you draw arrows to show balanced forces, both arrows should be the same size. If the forces are unbalanced, the biggest force should have the biggest arrow. The first one has been done for you.
5
Lesson 2– what forces act on objects that float and sink
Describe the movement of the boat in the pictures below, use the words balanced and unbalanced in your answer.
…………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… ………………................................................................................................ ................................................................................................................ ................................................................................................................ ................................................................................................................ ................................................................................................................ 6
Is there a connection between an objects density and whether it floats or sinks? Density is a measure of how much mass there is in 1 cm3 of something. Density depends on the mass of an object and its volume. You will measure a range of objects and work out the density of each. You will then test to see if each object floats or sinks.
Density=
Material
Mass (g)
Length (cm)
Height (cm)
Width (cm)
mass volume
Volume (cm3)
Density Floats 3 (g/cm ) or sinks?
Write a conclusion for this experiment……………………………………………………. …………………………………………………………………………………………………………………………… 7
You are going to find out if the amount of upthrust depends on the liquid. Even objects that sink have upthrust acting on them, but the upthrust is not big enough to make them float. You can measure upthrust by finding out how much the weight of an object changes when you put it in water. We can work out the upthrust of a liquid using the following equation: Upthrust = weight in air – weight in liquid
Your teacher will give you a sample of some different liquids, you will find out the upthrust of each liquid using the information above. You can work out the density of liquids by measuring out equal volumes and finding their mass. (remember density= mass/volume) After your experiment answer the following questions.: Does the upthrust depend on the kind of liquid?....................................... …………………………………………………………………………………………………………………………… What is the connection between the density of the liquid and the amount of upthrust it provides?.................................................................... …………………………………………………………………………………………………………………………… 8
Josh was in the sea at high tide when he came across a large stone under the water. He tried to lift the stone and was surprised to find that he could move it easily. He returned at low tide and found the stone out of the water. This time he could hardly move it.
The stone felt lighter when it was under ________________ . This is because ________________ was helping to push it up. The stone does not float because its ________________ is greater than the ________________ . The two forces which affect the stone are ________________ and ________________ . This is Danny floating in the water. Label the two forces.
Your weight is 600 N and you have just finished building a raft which weighs 1000 N. What is the total weight of you and the raft? ________________ What is the smallest upthrust force needed so that it will just float with you on it._______________________________________________________
9
Homework sheet
Name…………………………………………………….. Group……………
Archimedes lived in Syracuse, Italy, and was a great inventor and philosopher. One of the scientific facts that he discovered is called Archimedes’ Principle. The upthrust on something in a fluid is equal to the weight of fluid displaced. 1
2
a
What is the weight of the stone?......................................................................................
b
What is the upthrust on the stone when it is in the water?.......................................
c
What is the weight of the water in the small beaker?.................................................
d
Why doesn’t the stone float?..............................................................................................
If you compared the weight of the stone in air with its weight in water, the
difference would be the weight of the water displaced by the stone. This difference is the upthrust. a
What is the weight of the wooden block?........................................................................
b
What is the upthrust on the block?...................................................................................
c
What is the weight of the water in the small beaker?.................................................
d
Why does the wooden block float?....................................................................................
3
All the beakers have water in them.
a Which object is the heaviest?................................. How do you know?............................... ………………………………………………………………………………………………………………………………………………………………… b
Write the three objects in order of their weight, starting with the heaviest…………..
………………………………………………………………………………………………………………………………………………………………... Explain how you worked out your answer………………………………………………………………………………………. 4
a
What would happen if you put a 1 N weight on top of block Z?................................
………………………………………………………………………………………………………………………………………………………………... b
What would the extra water in the small beaker weigh?...........................................
……………………………………………………………………………………………………………………………………………………….. 5
Some of the things Archimedes invented are still in use today. Find out what an ‘Archimedes screw’ is and what it is used for……………………………………………………………………..
………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………………...
Lesson 2– what can forces act on a spring?
List some of the uses of springs in the space below.
You are going to investigate the forces that act on springs. First take a spring and push it down against the table and stretch it gently in your hands. Describe what you can feel and what happens to the spring……………………………………………………………………………………………………. …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… How is a spring stretched by different forces? You will set up a clamp, spring and ruler as shown in the diagram. You will hang different weights from the spring and measure how far the spring stretches. Record your results in a table in the space below.
Write a conclusion for your experiment here…………………………………………. …………………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………………… 10
Rock climbers and mountaineers use ropes to stop them getting hurt if they fall, but did you know that climbing ropes are stretchy?
Think about a spring like this chest expander. It is quite easy to stretch it a little way, but it takes a much bigger force to stretch it a long way. The amount of force from the spring depends on how far it has been stretched. The same thing happens with climbing ropes.
1
Label the force or forces acting on the falling climber in picture B?
2
a
Label the forces acting on the climber in C?
b
Are the forces balanced or unbalanced?..................................................................
c
What will happen to the falling speed of the climber?.........................................
3
Are the forces balanced or unbalanced in D? Balanced forces do not change the speed of something that is moving…………………………………………………………………………………...
4
a Will the climber fall further than the point she has already reached in D? Explain your answer…………………………………………………………………………………………………………….. b
What will happen to the force from the rope if she falls further? What effect will this have on her speed?............................................................................
…………………………………………………………………………………………………………………………………………………. 5
a If she had a stretchier rope than the one shown, would she fall further or not as far? What would happen if the rope was too stretchy? 11
The statements below are all about friction. Some are true, some are false, and some are partly true. Colour in the boxes at the top with a different colour then colour in the statements saying if they are true, partly true or false.
True
False
Partly true
Friction always slows things down.
Cars need friction to keep moving.
Cars need friction to stop.
You could not walk without friction.
Friction is useful to gymnasts.
Matches light because of friction.
Friction is useful to ships.
Shoelaces stay tied up because of friction.
You could not pick up a cup of tea without friction.
You could drink from a glass without friction.
Snow increases the friction between your shoes and the ground.
Friction is useful in playgrounds.
Pencils do not need friction to write.
There is no friction when you are rollerskating.
Imagine a world without friction. Try and describe some of the things you would and wouldn’t be able to do……………………………………………………………………………. ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………......... ........................................................................................................................................... ........................................................................................................................................... 13
Lesson 5– what is friction and what can it do?
Copy the sentences and fill in the missing words. The words you need are in the box. Force
Rough
Smooth
Surfaces
Friction is a ___________________ caused by two __________________ moving over each other. ___________________ surfaces produce more friction than _________________ surfaces. Look at these diagrams. Put a circle around the all the places where there is friction. One has been done for you.
3
Look at these pictures.
You pull the block along all of these surfaces.
It will be easiest to pull the block along the ___________________ . This is because it has the ___________________ (smoothest/roughest) surface, so there will be the ___________________ (most/least) friction. It will be hardest to pull the block along the ___________________. This is because it has the ___________________ (smoothest/roughest) surface, so there will be the ___________________ (most/least) friction. 14
Homework sheet
Name………………………………………………
Fill in the gaps in these sentences. Friction is a ____________ caused by two ____________ moving over each other. ____________ surfaces produce more friction than ____________ surfaces. Friction can be helpful, because it stops us ____________ when we walk, and ____________ that slow down cars or bicycles could not work without friction. Friction is not always useful. It can cause ____________ and ____________ , and ____________ away things that rub against each other. Oil can reduce the amount of ____________. Oil stops the surfaces touching each other. Liquids that reduce friction are called ____________ . Look carefully at these pictures.
On the other side of this sheet, for each picture: a
Describe where there is friction.
b
Say whether the friction is helpful or unhelpful.
c
Describe how the friction could be increased or decreased.
Can you match up the pictures to the speed they would move at?
37 km/h
240 km/h
6 km/h
8 cm/minute
750 km/h
25 cm/year
A car going at 30 mph covers 30 miles in each hour. Write out in words what the following figures mean: a
60 mph
____________________________________________
b
20 km/h ____________________________________________
c
40 m/s
____________________________________________
Look at the pictures again. a
The force that stops the racing car from skidding is called ______________________ .
b
Two forces are trying to make the racing car slow down. They are ______________________ and _____________________ ______________________ .
15
To work out a speed you have to know a distance and a time. You can calculate the speed using this formula: speed = distance/time Sometimes we know the speed of something, and we want to find out how far it will go in a certain time, or how long it will take to get somewhere. The formula can be arranged like this: distance = speed x time or time = distance/speed
1
The car on the motorway can travel 1860 metres in 60 seconds. Work out how fast the car is going. Don’t forget the units!
2
The dog runs 1980 metres in 5 minutes. How fast is he running? (Hint: Remember, there are 60 seconds in each minute.)
3
a
How far will the girl cycle in 1 hour? (Hint: 1 hour = 3600 seconds)
b
How far will the train go in 60 seconds?
c
How far will the cockroach run in 10 seconds?
4
How long will it take for the girl to cycle 4 km?
5
a
How many metres will the train travel in 1 hour?
b
How far is this in kilometres? 17
