Answer:
C. Lock the brakes is the answer
B. Pump the brakes
Answer:

Explanation:
From the question we are told that:
Mass 
Radius 
Angular velocity 
Radial force of 
Kinetic coefficient of friction 
Generally the equation for Kinetic Force is mathematically given by



Generally the equation for Torque on Center is mathematically given by

Where

Therefore



Therefore Angular acceleration of the grindstone is

Answer:
Is there a picture?
Explanation: I will answer if so plz put in comment box i cant do see t here thx. :)
Through the 1/r law, it was concluded that for the sound intensity or pressure is directly proportional to distance or radius. That is,
p = k/r
where k is the proportionality constant. If the distance of a sound wave is quadrupled then, the intensity of the sound is decreased to 1/4 of its original value.