A skateboarder, starting from rest, rolls down a 12.5-m ramp. When she arrives at the bottom of the ramp her speed is 6.45 m/s.

Question

(a) Determine the magnitude of her acceleration, assumed to be constant.

Answer 1

V = sqrt(2 a X) applies when the starting velocity is zero. , therefore

a = V^2/(2 X)= 1.664 m/s^2

Here's how you can derive it (if you can't remember it).

Average velocity = V/2
Time T = X/(V/2) = 2 X/V
Acceleration a = V/T = V^2/(2 X)