# Rotation

A cylinder of mass m is kept on the edge of a plank of mass 2m and length 12m, which in turn is kept on smooth ground.Coefficient of friction between plank an the cylinder is 0.1.The cylinder is given an impulse,which imparts a velocity 7m/s but no angular velocity. find the time after which the cylinder falls of the plank??

661
Gaurav Gardi ·

2s

• Abuturab Md not quite right The ans is 2.25s
1161
Akash Anand ·

Hints:

1)This is a condition for slipping condition, so we have to take friction to be max. between plank and cylinder.

2)Friction will act on both the bodies so transnational velocity of cylinder will decrease and of plank will increase. Angular velocity of the cylinder will also increase.

3) We have to find the time for which pure rolling starts, and during that we have to check the "RELATIVE DISTANCE" traveled by cylinder is equal to the length of the plank or not.

4)If not then after pure rolling starts we have to find the remaining time for the remaining part and add for the total time.