39.) More work is needed to carry a heavy suitcase slowly up a flight of stairs than to carry the same suitcase quickly up the same flight. True False

A 2,000 kg car is traveling at a rate of 40 m/s when an external force of 22,750 N, opposite in direction to the motion, caused a quarter reduction of speed, what is the coefficient of kinetic friction when the force was applied for 3 seconds? What is the work done by the force in decelerating the car?

A weight lifter lifts a 350-N set of weights from ground level to a position over his head, a vertical distance of 2.00m. How much does the weights lifter do, assuming he moves the weights at constant speed?

6) In a downhill ski race, surprisingly, little advantage is gained by getting a running start. (This is because the initial kinetic energy is small compared with the gain in gravitational potential energy even on small hills.) To demonstrate this, find the final speed in m/s and the time taken in seconds for a skier who skies 64.0 m along a 29° slope neglecting friction for the following two cases. (Enter the final speeds to at least one decimal place.)   (a) starting from rest final speed _____m/s time taken _____s   (b) starting with an initial speed of 3.00 m/s final speed _____m/s time taken _____s   (c) Does the answer surprise you? Discuss in detail why it is still advantageous to get a running start in very competitive events.