Goal: Comparing the relative size of forces from changes in position.
Source: UMPERG
Below is shown a strobe diagram indicating the position of four objects
at successive time intervals. The objects move from left to right.
During the intervals shown, which of the objects experiences the largest
net force?
- Object A only
- Object B only
- Object C only
- Object D only
- Objects A and B
- Objects B and C
- Objects A and C
- None of the above
- Cannot be determined
Commentary:
Answer
(9); It is not possible to determine the size of the net forces without
knowledge of the masses of the objects. Because the horizontal force in
(A) points initially to the left, then to the right, students may say
that the net force is zero, which is true only for a time average.