Question

A block of 70 kg  kg mass m climbs an incline plane which is making 85 degrees with the horizontal with an initial velocity 30 m/s .

How long time later does the block return to its initial position If the static, kinetic friction constant is 0.2 and gravity is 9.8m/s²?

Please write explicit solution

Answer 1

Distance covered during upward motion is

Now when block start moving Downward, Direction of friction Force will become in Upward direction parallel to incline,

Hence

Now acceleration is

Now from equation of motion;

Now from equation of motion

Time require to downward motion = 5.3232 seconds

Total time taken by block to return its initial position = 5.3232+3.02=8.34 seconds.