Need help with physics HW

1. Give an example of a situation in which there is a force and a displacement, but the force does no work. Explain why it does no work. 2. Consider the scenario to the right . A car for which friction Coasts Down is not negligible accelerates from rest down a hill, running Coasts Uo out of gasoline after a short distance. The driver lets the car Diver Great Roasts Down coast farther down the hill, then up and over a small crest. Stopa lor He then coasts down that hill into a gas station, where he Gacoling brakes to a stop and fills the tank with gasoline. Identify the forms of energy the car has, and how they are changed and transferred in this series of events. 3. A force F at an angle 0 above the horizontal is used to pull a heavy suitcase of weight mg a distance d along a level floor at constant velocity. The coefficient of friction between the floor and the suitcase is . The work done by the frictional force is: (A) - Fd cos 0 (B) - u Fd cos 0 (C] - u mgd (D) - u mgd cos 0 4. A 3.00 kg object is lifted 1.60 m above a floor then moved a horizontal distance of 2.00 m. What is work done by the gravitational force on the object? (A) -165 J (B) -47 J (C) 75 J (D) 118 1 5. A 3.00 kg object is lifted 1.60 m above a floor then moved a horizontal distance of 2.00 m. What is net work done on the object? [A) 106 J (B) 12 J (C) 75 J (D) 174 J 6. A 1.80 kg box is held in place at the top of a 30-degree incline and then released. It slides down the incline which is 1.20 m in length. If the coefficient of kinetic friction between the box and incline is 0.20. What is the potential energy of the box before it is released