# If an object with a mass of 2 kg  changes speed from 2 m/s to  5m/s, by how much does its kinetic energy change?

Jan 6, 2017

$11 J$

#### Explanation:

Kinetic energy is calculate dby the formula$\text{ } K E = \frac{1}{2} m {v}^{2}$

so in this case

$m = 2 k g , {v}_{1} = 2 m {s}^{- 1} , {v}_{2} = 5 m {s}^{- 1}$

$K {E}_{1} = \frac{1}{2} \times 2 \times {2}^{2} = 4 J$

$K {E}_{2} = \frac{1}{2} \times 2 \times {5}^{2} = 25 J$

$\Delta K E = K {E}_{2} - K {E}_{1} = 25 - 4 = 11 J$