Abox weighing 40.0 n, is initially at rest on a rough 6.0 m long ramp. the ramp is inclined at 30.0° with the horizontal. as the box slides down the ramp it experiences a frictional force of 6.0 n against its motion. determine the velocity of the box when it reaches the bottom of the ramp.

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?