In this video series, a marker is dropped onto a homemade “force plate”. Each video shows a different situation:

Video #1 (No Padding) – A marker is dropped directly onto the stick.  The marker impacts the stick, causing the laser beam to deflect.
Video #2 (With Padding) – A marker is dropped onto a piece of padding placed on top of the stick.  This time the laser beam deflects less.

Both videos were shot at 240 frames per second.

Before watching the videos, answer the following Pre-Lab Questions:

1. Before watching the videos, look at the photograph above.  What do you think happens to the width of the laser spot when you push down on the left side of the stick? [ When you push down on the left side of the stick the laser spot gets wider. / When you push down on the left side of the stick the laser spot gets narrower. ]
2. When the laser spot is narrow [ the force is small / the force is large ].
3. When the laser spot is wide [ the force is small / the force is large ].
4. If you were to drop a marker on the stick, the laser spot would [ shrink / grow wider ].
5. If you were to put padding on the stick, then drop a marker onto the padding, the laser spot would indicate [ more force / the same force / less force ] than if you were to drop the marker onto the stick without padding.

After watching both videos, answer the following Post-Lab Questions:

6. What is the peak force reached in Video #1? _______ Newtons
7. How long did the impulse last in Video #1? _________ seconds
8. What was the total impulse in Video #1? _________ Newton-seconds
9. What is the peak force reached in Video #2? _______ Newtons
10. How long did the impulse last in Video #2? _________ seconds
11. What was the total impulse in Video #2? _________ Newton-seconds
12. The peak force reached without padding was [ higher than / the same as / lower than ] the peak force reached with padding.
13. The time duration of the impact without padding was [ shorter than / the same as / longer than ] the time duration of impact with padding.
14. The total impulse without padding was [ more than double / roughly the same as / less than half ] the total impulse with padding.
15. The benefit of padding is that it [ shortens / lengthens ] the duration of impact, therefore [ reducing / increasing ] the impact force.

Challenge problem:

16. What is the momentum of the 0.008 kg marker after falling 2 cm?
17. Why is the impulse on the marker approximately the same regardless of whether or not padding was placed on top of the stick?
18. Use the data in the videos to verify the Impulse-Momentum Theorem for each video.  If the impulse on the stick does not perfectly match the change in momentum of the stick, why not?