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## Homework Statement

What are the average velocity and average acceleration of the tip of the 2.4-cm-long hour hand of a clock in the interval from 12p.m. to 6p.m.

I'm given the displacement which is 4.8 cm.

I know the motion takes six hours

I set my x axis at three-o-clock and my y-axis at 12

## Homework Equations

Average velocity = displacement / change in time

Average acceleration = change in velocity / change in time

I

## The Attempt at a Solution

The answer I get for velocity agrees with the back of the book:

Avg Velocity = -0.8 j cm/hr

But I have no clue how they get an average acceleration of -0.42 i cm/hr

^{2}.

I don't understand why there would be an average acceleration if the hand moves at a constant speed. I understand that a change in direction changes acceleration, but I'm missing something.