Motion Motion- A change in position with respect to a frame of reference.
Frame of reference: nonmoving point from which motion is measured Reference point
Motion
Distance vs Displacement Distance- the length of a path between two points. Displacement- the length of a straight line from the starting point to the ending point with a direction.
Speed Speed - distance traveled per unit time
• Speed is the rate of motion • Rate- anything that
happens over time
• Units for speed: mi/hr, km/hr, m/s, m/min
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Speed - practice 1. 2.
3.
Florence Griffith Joyner set a world record by running 200.0 m in 21.3 seconds. What was her speed? Suppose polar bears were running on land instead of swimming. If the polar bear runs at a speed of about 8.30 m/s, how far will it travel in 36 000 s? Put your answer in scientific notation. How much time does it take for a bird flying at at speed of 45 km/hr to travel a distance of 1800 km?
More Speed stuff Instantaneous
Speed - speed at a given instant Constant speed – speed that stays the same over time
Average Speed- total distance traveled over total time it took to travel that distance. Add up all the distances, add up all the times. Plug into the speed equation.
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Average Speed - practice 1.
You drive 200.0 miles in 3.00 hours. Then you stop at a rest stop for Wendy’s and to gas up the car. After your stop you travel 150.0 miles in 1.50 hours. What is your average speed for the entire trip?
Velocity
Velocity speed in a given direction can change even when the speed is constant Resultant velocity – when velocities are combined EX: bus moving at a velocity of 15 mi/hr, North You on the bus walking , your velocity is 1 mi/ hr N Resultant velocity = 16 mi/hr You on the bus walking again, but this time you’re walking in opposite direction the bus is going- your velocity is -1 mi/hr South Resultant velocity = 14 mi/hr
Velocity- practice If Justin races his Chevy S-10 north bound on Highway 235 for 2560.0 meters in 60.0 seconds. What is Justin’s velocity? http://www.youtube.com/watch?v=reAKFlbdhGY#t=91