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If the coefficient of friction is ... A hockey puck is given an initial speed of 20.0 m/s on a frozen pond. ... Friction Worksheet 6.2 kg F...

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1. A 7.6 kg object is resting on a horizontal surface. What is the normal force on the object? a. A force of 20 N pushes down on the object. Determine the normal force. b. A string is attached to the surface of the object and a person pulls upwards with 20 N. Determine the normal force. 2. A 7.6 kg object is pulled along a horizontal surface. If the coefficient of friction is 0.20, what is the force of friction? 3. A 9.6 kg object is pulled along a horizontal surface. If the coefficient of friction between the surfaces is 0.11, what is the force of friction? 4. A 20.0 N object is placed on a horizontal surface. A force of 3.0 N is required to keep the object moving at a constant speed, what is the coefficient of friction between the two surfaces? 5. A 16.2 kg object is pulled along a frictionless horizontal surface by a horizontal net force of 10.2 N. What is the normal force acting on the object? 6. A 6.2 kg object is pulled along a horizontal surface as shown in the diagram by a force of 22.0 N. If the acceleration of the object is 1.1 m/s2, what is the coefficient of friction between the surfaces? Ff

6.2 kg

T = 22.0N

7. A dockworker loading crates on a ship finds that a 20.0 kg crate, initially at rest on a horizontal surface, requires a 75 N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 60 N is required to keep it moving with a constant speed. a. Find the coefficient of static friction between the crate and the floor. b. Find the coefficient of kinetic friction between the crate and the floor. 8. A hockey puck is given an initial speed of 20.0 m/s on a frozen pond. The puck remains on the ice and slides 120 m before coming to rest. Determine the coefficient of kinetic friction between the puck and the ice. 9. A 64 kg box is resting on a carpet floor. If the coefficient of static friction between the box and floor is 0.98, what force is required to put the box in motion? 1

10. A car whose brakes are locked skids to a stop in 70 m from an initial velocity of 80 km/h. Find the coefficient of kinetic friction. 11. A box weighing 600 N is pushed along a horizontal floor at a constant velocity by a force of 250 N parallel to the floor. What is the coefficient of friction between the box and the floor? 12. A 1250 kg car traveling at 60.0 km/h comes to a sudden stop in 35 m. What is the coefficient of friction acting on the brakes? 13. A 950 kg car traveling at a constant velocity of 28 m/s, has a coefficient of friction of 0.125 acting on its axle. How much force is required by the engine to maintain its speed? 14. A 1425 kg dragster exerts 13900 N of force and accelerates from 0 to 100.0 km/h in 3.25 s. What is the coefficient of friction acting on the car?

Answer Key 1. 74 N 2. 15N 3. 10.35 N 4. 0.15 5. 158.76 N 6. 0.25 7. a. 0.38

b. 0.31

8. 0.17 9. 614.66 N 10. 0.36 11. 0.42 12. 0.40 13. 1200N 14. 0.123

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