LECTURE DEMONSTRATION MANUAL | Instructional Research Lab : ucla physics
Reaction Carts

M.6.3 Large and Small Reaction Carts

Choose two students, one heavy and one light, and stand them on the large reaction carts. When they push on each other's hands, the light student acquires a proportionally larger velocity than the heavier student.

Small reaction carts illustrate the same principle on the lecture table, as do gliders on an air track connected by a compressed spring.

Ask your students to answer from:

A. heavier person

B. lighter person

C. both the same

Which person feels the greater force? Which person gets the greatest

impulse? Which person undergoes the greater change in momentum?

Which person undergoes the largest acceleration?

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