# If an object with a mass of 2 kg  changes speed from 3 m/s to 5 m/s, by how much does its kinetic energy change?

Jan 3, 2016

I found $\Delta K = 16 J$ from this we deduce that energy was added to the system allowing it to accelerate and so change the velocity.
Kinetic Energy $K$ is given as:
$K = \frac{1}{2} m {v}^{2}$
$\Delta K = \frac{1}{2} m {v}_{f}^{2} - \frac{1}{2} m {v}_{i}^{2} = \frac{1}{2} m \left({v}_{f}^{2} - {v}_{i}^{2}\right)$
$\Delta K = \left(\frac{1}{\cancel{2}}\right) \cancel{2} \left({5}^{2} - {3}^{2}\right) = 25 - 9 = 16 J$