Question

How fast must a 1000 kg car be moving to have a kinetic energy of:

Answer 1

Answer:

$\mathrm{(a)}\: 2\: \mathrm{m/s}\\\mathrm{(b)}\: 20\: \mathrm{m/s}$

Explanation:

The kinetic energy of an object is given by $KE=\frac{1}{2}mv^2$ where $m$ is the mass of the object and $v$ is the velocity of the object.

We can set up the following equations with the information given:

$\mathrm{(a)}\: 2.0\cdot 10^3=\frac{1}{2}\cdot 1000\cdot v^2, \\v=\fbox{ 2\: \mathrm{m/s} }$

For part B, we have the same equation, but kinetic energy is now $2.0\cdot 10^5$.

Therefore:

$\mathrm{(b)}\: 2.0\cdot 10^5=\frac{1}{2}\cdot 1000\cdot v^2, \\v=\fbox{ 20\: \mathrm{m/s} }$.