XAVIER CATHOLIC COLLEGE PHYSICS THE WORLD ...
XAVIER CATHOLIC COLLEGE
PHYSICS
THE WORLD COMMUNICATES
Worksheet 5: • 2.4
Students : explain an echo as a reflection of a sound wave
(Dobinson; 1997: 33)
1. Two springs are connected as above and a wave motion is imparted to the heavy spring from the left-hand end. Kate, an observer, watches the motion from the side as it moves through the two springs. Suggest what she might see as the waves move into the lighter spring with regard to: a. the speed of the crests and troughs from left to right; b. the distance apart of the crests and troughs; c. the number of crests and troughs passing point X in a minute compared to the number of crests and troughs passing point Y in a minute.
(Dobinson; 1997: 33)
2. Grace sends a single pulse down a spring which is fixed securely to a wall (as shown above). She is surprised to see that, not only does it come back to her, but it is also ‘upside-down’. W5-2.4-Reflection of Pulses & Waves.doc
Page 1 of 4
(Dobinson; 1997: 33)
a. What is the process of ‘bouncing’ off an object called? b. What term is used to describe the turning ‘upside-down’ of a wave? c. Which of Newton’s laws explains why (b) occurs? 3. Grace decides to ‘beat the system’ and connects the spring in the above question to thin vertical pole with a loose sliding loop. She connects the spring to the loop and repeats the sending of the pulse.
(Dobinson; 1997: 33)
And back it comes! This time there is no ‘upside down’ effect as the pulse returns.
(Dobinson; 1997: 33)
Explain why the pulse returns to Grace in the upright position. 4. Kate and Grace return to the set-up in the first question. One of them sends a single pulse down the heavy spring as before and they both watch the region around point A. They look for ‘bounce back’ and transmission.
(Dobinson; 1997: 33)
Draw a simple diagram to show what they would see in springs X and Y a short time after the pulse had reached point A. 5. The order of the springs is now reversed (i.e. the lighter, more elastic spring first). The same pulse is sent down the lighter spring. Draw a diagram to show what would happen in springs Y and X a short time after the pulse passes A.
W5-2.4-Reflection of Pulses & Waves.doc
Page 2 of 4
W5-2.4-Reflection of Pulses & Waves.doc
Page 3 of 4
Acknowledgements Dobinson, G. (1997) Instant Lessons in Physics Book 1 . Strathfield, Emerald City Books
W5-2.4-Reflection of Pulses & Waves.doc
Page 4 of 4
PHYSICS
THE WORLD COMMUNICATES
Worksheet 5: • 2.4
Students : explain an echo as a reflection of a sound wave
(Dobinson; 1997: 33)
1. Two springs are connected as above and a wave motion is imparted to the heavy spring from the left-hand end. Kate, an observer, watches the motion from the side as it moves through the two springs. Suggest what she might see as the waves move into the lighter spring with regard to: a. the speed of the crests and troughs from left to right; b. the distance apart of the crests and troughs; c. the number of crests and troughs passing point X in a minute compared to the number of crests and troughs passing point Y in a minute.
(Dobinson; 1997: 33)
2. Grace sends a single pulse down a spring which is fixed securely to a wall (as shown above). She is surprised to see that, not only does it come back to her, but it is also ‘upside-down’. W5-2.4-Reflection of Pulses & Waves.doc
Page 1 of 4
(Dobinson; 1997: 33)
a. What is the process of ‘bouncing’ off an object called? b. What term is used to describe the turning ‘upside-down’ of a wave? c. Which of Newton’s laws explains why (b) occurs? 3. Grace decides to ‘beat the system’ and connects the spring in the above question to thin vertical pole with a loose sliding loop. She connects the spring to the loop and repeats the sending of the pulse.
(Dobinson; 1997: 33)
And back it comes! This time there is no ‘upside down’ effect as the pulse returns.
(Dobinson; 1997: 33)
Explain why the pulse returns to Grace in the upright position. 4. Kate and Grace return to the set-up in the first question. One of them sends a single pulse down the heavy spring as before and they both watch the region around point A. They look for ‘bounce back’ and transmission.
(Dobinson; 1997: 33)
Draw a simple diagram to show what they would see in springs X and Y a short time after the pulse had reached point A. 5. The order of the springs is now reversed (i.e. the lighter, more elastic spring first). The same pulse is sent down the lighter spring. Draw a diagram to show what would happen in springs Y and X a short time after the pulse passes A.
W5-2.4-Reflection of Pulses & Waves.doc
Page 2 of 4
W5-2.4-Reflection of Pulses & Waves.doc
Page 3 of 4
Acknowledgements Dobinson, G. (1997) Instant Lessons in Physics Book 1 . Strathfield, Emerald City Books
W5-2.4-Reflection of Pulses & Waves.doc
Page 4 of 4
