A small 350-gram ball on the end of a thin, light rod is rotated in a horizontal

Question

A small 350-gram ball on the end of a thin, light rod is rotated in a horizontal circle of radius 1.1 m

Part A

Calculate the moment of inertia of the ball about the center of the circle.

Express your answer using two significant figures.

Part B

Calculate the torque needed to keep the ball rotating at constant angular velocity if air resistance exerts a force of 0.029 N on the ball. Ignore the rod's moment of inertia and air resistance.

Express your answer using two significant figures.

Explanation / Answer

moment of inertia of object R distance from rotation axis = MR^2

MOI of ball = (350/1000) (1.1)^2 = 0.4235 Kgm2

= 0.42 kgm2

for constant velocity

net torque = 0

Torque required (in other direction) = 0.029 *1.1

= 0.0319 Nm

=0.032 Nm

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