Question

A 4.4-cm-diameter, 24 g plastic ball is attached to a 1.2-m-long string and swung in a vertical circle. The ball’s speed is 6.1 m/s at the point where it is moving straight up. What is the magnitude of the net force on the ball? Air resistance is not negligible.

Short answer

The Net force on the ball is = 0.7308 N

Step-by-step solution

Given Information 

Ball diameter = 4.4-cm-diameter,

mass =24 g

String length = 1.2-m

v= 6.1 m/s

Explanation

First draw a diagram as below

From the figure find the T as below

$$\begin{gathered} T=\frac{m{v}^2}{r} \\ T=\frac{(0.024kg)\times (6.1m/s{)}^2}{1.222m} \\ T=0.7308\mathrm{N} \end{gathered}$$

So the radius will be = 1.2m+2.2 cm = 1.222m

Centripetal force is given by $F=\frac{m{v}^2}{r}$

This force is equal to tension on the string

So the force is 0.7308 N