- #1

teresalin2004

- 2

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## Homework Statement

At a playground you let your kid sister (30 kg) kneel on the surface (near the edge) of a 2.1 meter diameter merry-go-round. You push the merry-go-round so that it constantly accelerates from rest to a final speed of 1.7 rotations per second at the end of a 25 second interval. (please complete all questions using radians)

After it comes up to speed, you stop pushing and the merry-go-round continues to run at a constant rate of 1.7 rotations per second. What is the magnitude of your sister's acceleration, if any?

## Homework Equations

V is the tangental velocity in m/s

r is radius of circle in meters

ω is angular velocity in radians/sec

a is in m/s²

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1.7 rotations per second x 2π rad/rev = 10.68 rad/s

ang. acc. = Δω/Δt = 10.68/25 = 0.427 rad/s²

134 rad x 1 rev/2πrad = 21.25 rev

## The Attempt at a Solution

I got the first part of the question right, but I have no idea what I am doing wrong for the last part shown above. This is what I did:

a = rω² = (2.1)(10.68)² = 240 m/s²

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