# If an object with a mass of 5 kg  changes speed from 5m/s to  7m/s, by how much does its kinetic energy change?

Apr 3, 2016

Equation: ${E}_{k} = \frac{1}{2} \cdot m \cdot {v}^{2}$

#### Explanation:

At $5 m / s$: ${E}_{k} = \frac{1}{2} \cdot 5 \cdot {5}^{2} = 62.5 J$

At $7 m / s$: ${E}_{k} = \frac{1}{2} \cdot 5 \cdot {7}^{2} = 122.5 J$

Difference: $122.5 - 62.5 = 60 J$

${\left(\frac{7}{5}\right)}^{2} = 1.96$, allmost double. Check!