# What is the kinetic energy of an object with a mass of 10 kg that has been in freefall for 2 s?

##### 1 Answer
Jan 9, 2016

I found $K = 1 , 920 , 8 J$

#### Explanation:

There are two ways to find this:
1) evaluate the velocity and use, for the kinetic energy, $K = \frac{1}{2} m {v}^{2}$;
2) evaluate the potential energy $U$ at the start that will be converted into kinetic energy:

From this:
$U = m g h = 10 \cdot 9.8 \cdot 19.6 = 1 , 920.8 J$
This potential energy at the top will be changed entirely into kinetic energy (neglecting friction).