7. (3.10) Consider the diagram representing a " 30.0 portion of an amusement park ride. A 100 kg car A 30- has 30,000 ] of Potential Energy at point A D where it is at rest. The car then rolls along the 20 -+- - track from A to D. Assume the car and track 10 HI- - system is closed and isolated. C What is the value of the kinetic energy of the car at 2 my ? point D? * B. 10,000 J C. 20,000 J D. 30,000 J 2 ( 100 ) 8. (3.11) A truck is pulled up an inclined plane at constant speed by an electric motor. The gain in potential energy of the truck is 48 kJ. The efficiency of the electric motor is ? How much energy is dissipated in pulling the truck up the plane? lass B. 24 kj WIN C. 32 kJ 1 . 64 KI13. (4.4) A ball of mass 2.0 kg falls vertically and hits the ground with speed 7.0 m-s" as shown below. 7.0 my"] AP_ Am AV P V O m 3.0 ms before after The ball leaves the ground with a vertical speed 3.0 m-s". The magnitude of the change in momentum of the ball is X A. zero. 8.0 kg m/s. C. 10 kg m/5. D. 20 kg m/5