Goal: Hone the concept of impulse
Source: UMPERG-ctqpe80
A MOVING car collides with a STATIONARY truck. Which of the following
statements is true about the magnitudes of the impulse on each due to
the other?
- The impulse on the car is larger than the impulse on the truck.
- The impulse on the truck is larger than the impulse on the car.
- The magnitudes of the two impulses are equal.
- Answer depends upon circumstances of the collision.
Commentary:
Answer
(3) The 3rd law requires that the impulses be equal. Even
students who understand the 3rd law have difficulty realizing that the
magnitude of the impulse on two interacting bodies is the same. Many
students, however, do not understand impulse enough to recognize the
association. Others do not read the problem carefully enough and answer
with regard to ALL the forces, not just the one due to the other
vehicle.