15. A pulley system is set up to help lift a car off the ground. If the car has a mass of 1440 kg, and it requires a force of 4.75 kN to lift the car. what is the mechanical advantage of the pulley system? 16. Terrance uses a ramp to get sound equipment onto a 2.1 m stage. One speaker has a mass of 65 kg. In order to get this speaker up the ramp, Terrence has to push with a force of 290 N, over a distance of 6.4 m. What is the efficiency of this ramp? Practice 7. Janine is riding a bicycle. Over a period of 8.90 second, she increases her speed from 0 m/s to 7.57 m/s. If the combined weight of Janine and her bicycle is 89.3 kg, how much power, on average, did Janine produce during this period? 8. How fast will a 74.3 kg person have to run to achieve a momentum of 404 49.m? 9. Carrie is pushing a 39.8 kg shopping cart at a speed of 0.744 m/s. If she applies a force of 6.59 N, for a period of 2.05 seconds, what will be the speed of the shopping cart after this force is applied? -on to the next page- 10. Two bowling balls, one green and one purple, are rolling along a track back towards the bowlers. The green ball has a mass of 5.9 kg, and is moving in the positive direction at a speed of 2.85 m/s. The purple ball, which is in front of the green ball, has a mass of 7.2 kg, and is moving in the positive direction at a speed of 1.25 m/s. After the green ball strikes the purple ball, the green ball's speed drops to 1.05 m/s. What is the velocity of the purple ball after this collision?11. Two magnets are sliding towards each other. One of the magnets. which has a mass of125 grams. is moving in the positive x-direction at a speed of 7.33 mils. The other magnet, which has a mass of 85.0 grams. is moving in the negative ir-direction at a speed of 11.9 m/s. When thev collide. thev bind together. and move as a single unit. What is the velocitv ofthis single unit immediatelv after the collision? 12. A trail maintenance team is using explosives to remove a 895 kg boulder from a trail. When the explosive charge is detonated, the boulder splits into two parts. The larger part has a mass of 515 kg. and moves west at a speed of 3.4 mfs. What is the velocity of the smaller part? 13. Janelle is tightening a bolt on her car. which requires her to twist the bolt clockwise. The wrench she is using has a length of 24 cm. If she pulls on the wrench handle with a force of 16 N. what torque is she exerting on the bolt? Assume that herforce is perpendicular to the wrench handle. on to the next page 14. To help keep heating costs down. Richard installs a spring that connects the door to the doorframe. allowing the door to automatically close. When the door is opened to a certain distance, the spring exerts a 22 N force. with a lever arm of41 cm. The angle between the force vector and lever arm is 64. If this setup rotates the door counterclockwise, what is the torque vector exerted on the door