Question

What is the speed of a 0.2 kg baseball if its kinetic energy is 40 j?

Answer 1

The kinetic energy of an object is given by:

$K=\frac{1}{2}mv^2$

where m is the mass of the object and v its speed. The ball in this problem has a mass of m=0.2 kg and a kinetic energy of K=40 J, so we can rearrange the previous equation to find its speed:

$v=\sqrt{\frac{2K}{m}} =\sqrt{\frac{2 \cdot 40 J}{0.2 kg}}=20 m/s$