a motorcyclist drives from a to b with the uniform speed of 30 km/h-1 and returns back with the speed of 20 km/h-1.find the average speed?

Explain why electric current cannot exist if a current doesn't have a voltage source.

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.

Aparticle moves in a circle 1.50 m in radius . through what angle in radians does it rotate if it moves through an arc length of 2.50m? what is the angle in degrees?