Question

When given a question such as…“During an experiment, an object is placed on a disk that rotates about an axle through its center, as shown in Figure 1. The disk is a distance R =0.10  m from the center and rotates with a constant tangential speed of 0.60 ms. A free body diagram of the forces exerted on the block is shown in Figure 2 with an unknown force of friction. What is the force of friction exerted on the object?“How do I know what formula to use to plug in my values to?

Answer 1

0.72 N

Explanation:

Due to the rotation, the centrifugal force is also worked in the outward direction.

Then the friction force is equal to:

`F_C=(mv^2)/(r)`

We calculate the mass, like this.

`\begin{gathered} F=m\cdot g \\ m=(F)/(g)=(2)/(9.81) \\ m=0.2\text{ kg} \end{gathered}`

Replacing:

`\begin{gathered} F_C=(0.2\cdot0.6^2)/(0.1) \\ F_C=0.72\text{ N} \end{gathered}`