Question

If a stone has 390 J of energy and is moving with
a speed of 12 m/s, what is the mass of the stone?

Answer 1

Answer:

5.4 g

Explanation:

The stone is already in motion, so the only energy it has is kinetic. The formula for kinetic energy is:

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

You can substitute the 390 J in for KE and 12 m/s in for v. After that, the equation looks like:

$390=\frac{1}{2} m12^{2}$

Then do basic algebra and m=5.4 g