A2L Item 034
- Description: Determine the relative size of the net force from a strobe diagram.
- Goal: Comparing the relative size of forces from changes in position.
- Source: UMPERG
- Keywords: Mechanics, Graphing, Forces
The question for students:
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 for teachers:
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.