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course Phy 121
A steel ball of mass 110 grams moves with a speed of 30 cm / second around a circle of radius 20 cm. What are the magnitude and direction of the centripetal acceleration of the ball?
answer/question/discussion:
aCent=v^2/r
aCent=(30cm/s)/20cm
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You didn't square v.
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aCent=1.5cm/s^2
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The units of your calculation would be 1 / s, not cm/s^2.
If you square the v the units will work out correctly.
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The direction would be towards the center of the circle.
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What is the magnitude and direction of the centripetal force required to keep it moving around this circle?
answer/question/discussion:
F=M*a
F=.11kg*1.5m/s^2
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This would be OK had you squared that v to find the correct acceleration.
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F=.165N
This force would be directed perpendicular to the radius of the circle.
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