# A 10 kg mass has a KE of 125 J, what is its velocity?

Dec 9, 2015

5 m/s

#### Explanation:

$E K = \frac{1}{2} m {v}^{2}$

Given: $E K = 125 J = 125 k g {m}^{2} / {s}^{2} , m = 10 k g$

So ${v}^{2} = \frac{2 E K}{m}$ and $v = \sqrt{\frac{2 E K}{m}}$

$v = \sqrt{\frac{2 \cdot 125 \frac{k g {m}^{2}}{s} ^ 2}{10 k g}} = \sqrt{25 {m}^{2} / {s}^{2}} = 5 \frac{m}{s}$

Note: I solve the units first; it helps prevent mistakes.