Lab Video Lab: Cart Push #2 and #3
This lab is based on two Direct Measurement Videos called Cart Push-off #2 and Cart Push-off #3 released on the Science Education Research Center (SERC) website. The copyright for these videos belongs to Independent School District 197 in Mendota Heights MN. The project is partially funded by a National Science Foundation Grant (#1245268) awarded in September 2013.

The following lab directions were designed for use in my Honors Physics I class and only represent one method of analyzing the data provided in the video.

When the video Cart Push-off#2 opens, three students on “skateboards” are poised to push off each other. Note that there are lines marked 0 cm and 20 cm on the bottom edges of side of the screen.

The masses for the participants are listed as:
• Cart mass = 22 ± 0.2 kg
• Christine’s mass = 57.8 ± 0.2 kg
• Hailey’s mass = 68.6 ± 0.2 kg
• Connor’s mass = 69.4 ± 0.2 kg

 What is the frame rate?

 On which frame did the back edge of BOTH carts first reach the 0-cm mark?

 On which frame did the back edge of Connor’s cart reach the 20-cm mark?

 On which frame did the back edge of Christine’s and Hailey’s cart reach the 20-cm mark?

Refer to the following information for the next seven questions.

Analysis
 By using the frame rate, calculate the time required for the back edge of Connor's cart to travel through the delineated 20-cm interval.

 By using the frame rate, calculate the time required for the back edge of Christine and Halley's cart to travel through the delineated 20-cm interval.

 What was the average velocity (VECTOR) of Connor's cart moving as it travelled through the delineated 20-cm interval?

 What was the average velocity (VECTOR) of Christine and Hailey's cart moving as it travelled through the delineated 20-cm interval?

 Calculate the momentum (VECTOR) of Connor and his cart as they travelled through the delineated 20-cm interval.

 Calculate the momentum (VECTOR) of Hailey and Christine and their cart as they travelled through the delineated 20-cm interval.

 Calculate the TOTAL momentum of all three students and both carts in frame +100.

Refer to the following information for the next two questions.

Conclusion
Based on the procedure used to analyze Cart Push-off #2, you will now analyze the video Cart Push-off #3.

How does the mass of the boy in the checkered shirt compare to Christine’s mass in Cart Push-off #3?
 Support your previous answer quantitatively (numerically). EC will be given for the correct mass. Otherwise, you may use a comparison of time needed for each participant or a comparison of their velocities as part of your supporting statement.