If an object with a mass of 2 kg  changes speed from 19m/s to 20 m/s, by how much does its kinetic energy change?

Jan 16, 2016

$39 J$, increase

Explanation:

Kinetic Energy of an object is given by
${E}_{k} = \frac{1}{2} m {v}^{2}$, where $m$ is the mass and $v$ the velocity* of the body.
In the given question, if ${v}_{i}$ and ${v}_{f}$ are the final and initial velocities respectively
Change in kinetic energy $\Delta {E}_{k} = \frac{1}{2} m \left({v}_{f}^{2} - {v}_{i}^{2}\right)$
Substituting given values
$\Delta {E}_{k} = \frac{1}{2} .2 . \left({20}^{2} - {19}^{2}\right)$

*Even though velocity is a vector quantity, Kinetic energy is a scaler quantity because ${v}^{2}$ i a scaler quantity.