Academics

Forces In Collisions

 

Physics Lab Manual

The purpose of this lab is to predict the size and profile of forces that occur in collisions between two carts.

Part A: Introduction

In general, the force profile in a collision is something like that shown below. There is no force until the two objects touch. Then the force magnitude increases until some maximum value, then the force decreases to zero again as they move apart. In a collision where no energy is lost, we could expect the force curve to be symmetrical, but in most cases, it takes a little longer for the force to go to zero than it took for it to increase from zero to its maximum value.

Force

time

Part B: Predictions

For each of the situations below, draw a force profile showing the force acting on Cart A, given the profile of the force that is acting on Cart B. (That is show if you think the force felt by Cart A is larger or smaller than the force felt by Cart B and if its profile is different.)

  1. Cart A and Cart B have the same mass and same speed:

    Force felt by B

    time

    Cart A

    Cart B

    v

    v

    Force felt by A?

  2. Cart A and Cart B have the same mass but Cart B is at rest:

    Force felt by B

    time

    Cart A

    Cart B

    v

    v = 0

    Force felt by A?

  3. Cart A has four times the mass of Cart B. Cart B is still at rest:

    Force felt by B

    time

    Cart A

    Cart B

    v

    v = 0

    Force felt by A?

  4. Cart A has four times the mass of Cart B. Cart A is at rest.

    Force felt by B

    time

    Cart A

    Cart B

    v

    Force felt by A?

    v = 0

Part C: Conclusions

After watching the actual collisions and seeing the force profiles, correct in a different color (if necessary) the force profiles for the Cart A. What overall conclusion do you make regarding the forces felt by two objects that collide with each other?