Question

a small block of mass m sits on a horizontally rotating platform, a distance r from the axis of rotation. the coefficient of static friction between the block and the platform is μs and the maximum speed the block can have before sliding along the rotating platform is vmax. the platform rotates at a constant rate and the blocks speed v is such that 0 < v < vmax. which expression represents the net force exerted on the block while the platform is rotating?
a 0
b $\frac{mv^{2}}{r}$
c μsmg

Explanation:

Step1: Identify the type of motion

The block is in uniform - circular motion on the rotating platform.

Step2: Recall the centripetal - force formula

For an object in uniform - circular motion of mass $M$, speed $v$, and radius of the circular path $R$, the centripetal force $F_c$ (which is the net force in this case) is given by $F_c=\frac{Mv^{2}}{R}$.

Answer:

B. $\frac{Mv^{2}}{R}$