# physics (please help elena)

posted by
**Steven** on
.

We will now examine how much time we need to stop a ship-engine-like cylinder. Suppose you take a rotating cylinder and let it roll to the right until it reaches a vertical wall. It then spins against the two walls as shown in the picture, slowly slowing down. How much time will it take in s for the cylinder to stop? The initial velocity of cylinder's surface when it touches the vertical wall is 30 m/s.

Its length is l=10 m, its radius is r=0.5 m and it's made out of wood of density ρ=800 kg/m3.

The coefficient of friction between the cylinder and the walls is μ=0.3.