*Question 1*:
A force **F** pushes a ball as the ball moves
a displacement **s**.
The ball

- speeds up
- slows down
- neither

Answer: it speeds up, since the work done by the force during the displacement, F dot s, is positive

*Question 2*:
A force **F** pushes a ball as the ball moves
a displacement **s**.
The ball

- speeds up
- slows down
- neither

Answer: neither, since vectors F and s are perpendicular: the dot product of F and s is zero.

*Question 3*:
Estimate the work done on the ball due to the force
as the ball moves as shown.

Answer: the work done on the ball by the force is work = F dot s = F * s * cos(angle between) The angle between the vectors is about 110 degrees, which is more than 90 degrees -- so the work done will be negative. = something between -15 Joules and 0 Joules

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This page maintained by Michael Richmond.
Last modified Jan 29, 2002.
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Copyright © Michael Richmond. This work is licensed under a Creative Commons License.