Answer:
Explanation:
We shall apply conservation of mechanical energy .
initial kinetic energy = 1/2 m v²
= .5 x m x 12 x 12
= 72 m
This energy will be spent to store potential energy . if h be the height attained
potential energy = mgh , h is vertical height attined by block
= mg l sin20 where l is length up the inclined plane
for conservation of mechanical energy
initial kinetic energy = potential energy
72 m = mg l sin20
l = 72 / g sin20
= 21.5 m
deceleration on inclined plane = g sin20
= 3.35 m /s²
v = u - at
t = v - u / a
= (12 - 0) / 3.35
= 3.58 s
it will take the same time to come back . total time taken to reach original point = 2 x 3.58
= 7.16 s
