# A ball starting from rest accelerated uniformly at 5.0 m/s as it rolls 40 meters down an incline. How much time is required for the ball to roll the 40 meters?

Nov 19, 2015

$4 \text{s}$

#### Explanation:

Firstly we can get the final velocity of the ball using:

${v}^{2} = {u}^{2} + 2 a s$

I will assume $a = 5 {\text{m/s}}^{2}$

$\therefore {v}^{2} = 0 + 2 \times 5 \times 40 = 400$

$\therefore v = \sqrt{400} = 20 \text{m/s}$

Now we can get the time using:

$v = u + a t$

$\therefore 20 = 0 + 5 \times t$

$t = \frac{20}{5} = 4 \text{s}$