Answer:
A. 42.3 revolution per minute
B. Centripetal Force
Explanation:
20 g = 0.02 kg
5 cm = 0.05 m
Let g = 9.8 m/s2
A.The friction force acting on the eraser is the product of normal force and its coefficient:
For the eraser to begin slipping, its centripetal acceleration must win over the acceleration created by friction force, which is
We can calculate the angular velocity from this:
where r = 0.05 is the radius of rotation, which is distance from the center to the eraser
If it spins and angle of 4.43 rad per second then for every minute (60 seconds) it would spin an angle of 4.43 * 60 = 265.6 rad/min
Since 1 revolution is 2π rad, then in a minute it would spin 265.6 / 2π = 42.3 revolution/minute
B. The force responsible for making the eraser go faster while the turntable is spinning up would be the centripetal force.