A physics professor is pushed up a ramp inclined upward at 30degrees above the horizontal as he sits his desk chair that slides on frictionless rollers. the combined mass of the professor and the chair is 90kg. he is pushed 2.60m along the incline by a group of students who together exert a constant horizontal force of 600N. the professor speed at the bottom of the ramp is 1.75m/s. use the work-energy theorem to find his speed at the top of the ramp.