Question

A 54 kg cannon ball has 27378 J of KE. How fast is it going? Round to nearest whole.

Answer 1

Kinetic energy of a body of mass m is given by,

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

where v is the speed of the body,

Given,

$\begin{gathered} m=54\text{ }kg \\ K.E.=27378\text{ }J \end{gathered}$

Therefore,

$\begin{gathered} 27378=\frac{1}{2}(54)v^2 \\ \Rightarrow v=\sqrt{\frac{2\times27378}{54}}\text{ }\frac{m}{s} \\ \Rightarrow v=31.84\text{ m/s or 32 m/s} \end{gathered}$

Result: The cannon ball is going at a speed of 32 m/s.