Question

A car is sitting at the top of an inclined plane, which is 5.2 meters long and meets the horizontal at an angle of 12 degrees. The cart is then allowed to roll to the bottom of the incline. What will be the velocity of the cart at the bottom of the incline. (4.61m/s)

Please help me!!

I tried to solve it:
mgh=1/2mv^2
(resulted in incorrect answer?)

Answer 1

(1/2) m v^2 = m g h
so
v^2 = 2 g h

h = 5.2 sin 12
so
v^2 = 2 * 9.8 * 5.2 * sin 12

v^2 = 21.2
v = 4.60