If an object with a mass of 2 kg  changes speed from 14 m/s to  15m/s, by how much does its kinetic energy change?

Jan 21, 2016

Change in kinetic energy can be calculated using
$\Delta {E}_{k} = \frac{1}{2} m \left({v}_{f}^{2} - {v}_{i}^{2}\right)$

Explanation:

Kinetic energy is calculated using:

${E}_{k} = \frac{1}{2} m {v}^{2}$
Change in ${E}_{k}$ is just final minus initial, or
$\Delta {E}_{k} = \frac{1}{2} m {v}_{f}^{2} - \frac{1}{2} m {v}_{i}^{2}$

which factors to

$\Delta {E}_{k} = \frac{1}{2} m \left({v}_{f}^{2} - {v}_{i}^{2}\right)$

So, in this case,

$\Delta {E}_{k} = \frac{1}{2} 2 k g \left({15}^{2} - {14}^{2}\right)$

$\Delta {E}_{k} = 29 J$