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course PHY 121

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cq_1_031PHY 121

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The problem:

A ball starts with velocity 0 and accelerates uniformly down a ramp of length 30 cm, covering the distance in 5 seconds.

• What is its average velocity?

*30cm / 5 sec = 6cm/s

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• If the acceleration of the ball is uniform then its average velocity is equal to the average of its initial and final velocities.

You know its average velocity, and you know the initial velocity is zero.

What therefore must be the final velocity?

**6cm/s *2= 12cm/s

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• By how much did its velocity therefore change?

*12cm/s / 5s = 2.4cm/s

####12cm/s – 0cm/s = 12cm/s

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• At what average rate did its velocity change with respect to clock time?

*2.4cm/s * 1s =2.4cm/s^2

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• What would a graph of its velocity vs. clock time look like? Give the best description you can.

*The graph would have an increasing, linear line going from 0 up to 12cm/s with 6cm/s being at the midpoint.

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30 min

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