Question

A 2 kg object has a kinetic energy of 64 J. What is its momentum?

Answer 1

Take into account that the momentum is given by:

$p=mv$

where m is the mass and v the speed of motion.

In order to calculate p it is necessary to find the value of v. Use the following expression for the kinetic energy:

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

In this case, you have:

K = 64J

m = 2 kg

Solve for v and replace the previous values:

$\begin{gathered} v=\sqrt{\frac{2K}{m}} \\ v=\sqrt[]{\frac{2(64J)}{2\operatorname{kg}}}=8\frac{m}{s} \end{gathered}$

Now, replace the value of v and m to find the momentum:

$p=(2kg)(8\frac{m}{s})=16\operatorname{kg}\cdot\frac{m}{s}$

Hence, the momentum is 16 kg*m/s