P. 3976. A disc of radius R is moved with a constant u velocity on an air-cushioned table. Another small disc collides with it elastically with a speed of v0=0.3 m/s, the velocities of the discs are parallel. The distance d shown in the figure is equal to R/2, friction between the discs is negligible.
a) For which u will the small disc move perpendicularly to its original motion after the collision?
b) What will be the speed of the small disc in this case?
P. 3978. A rod of mass m and length =1 m slides down on a slope such that one of its end slides along the slope and the other slides along the horizontal without friction. Initially the rod touches the incline, the figure shows a snapshot of the motion later.
a) Find the speed of the endpoints A and B when the rod reaches the horizontal position.
b) What are these speeds when the rod encloses an angle of 30o with the horizontal.
P. 3981. A generator of constant voltage but of variable frequency is connected to a series RLC circuit. Gradually changing the frequency the current reaches a maximum, when the voltage across the inductor is U1. If the frequency is further increased the current decreases, but the voltage across the inductor still increases. Later the voltage across the coil reaches its maximum of U2 and then it decreases.
Determine the quotient of in terms of R, L and C.