A horizontal plane with the coefficient of friction `k` supports two bodies: a bar and an electric motor with a battery on a block. A thread attached to the bar is wound on the shaft of the electric motor. The distance between the bar and the electric motor is equal to `l`. When the motor is switched on, the bar, whose mass is twice as great as that of the other body, starts moving with a constant acceleration `w`. How soon will the bodies collide?

Answer

`[t=sqrt((2L)/(3a+mug))]`