# If we know the total energy in a system is 30 J, and we know the PE is 20 J, what is the KE?

Apr 20, 2018

The Kinetic Energy in the system is 10 J

#### Explanation:

The total mechanical energy in a closed system is always the sum of the potential and the kinetic energies.

$K E + P E = T E$

$K E = T E - P E$

$K E = 30 J - 20 J$

$K E = 10 J$