Ms. Mulrooney Physics Worksheet: Coefficients of Friction and Overcoming Friction 1. A bag of sugar has a mass of 2.26 kg. a. What is its weight in newtons on the moon, where the acceleration due to gravity is one-sixth that on Earth? b. What is its weight on Jupiter, where the acceleration due to gravity is 2.64 times that on Earth? 2. A 2.0 kg block on an incline at 60.0˚ angle is held in equilibrium by a horizontal force. a. Determine the magnitude of this horizontal force (disregard friction). b. Determine the magnitude of the normal force on the block. 3. A 24 kg crate at rest on a horizontal floor requires a 75 N horizontal force to set it in motion. Once it is in motion, a horizontal force of 53 N keeps it moving with a constant velocity. 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. 4. A 25 kg chair initially at rest on a horizontal floor requires a 165 N horizontal force to set it in motion. Once the chair is in motion, a 127 N horizontal force keeps it moving at constant velocity. a. Find the coefficient of static friction between the chair and the floor. b. Find the coefficient of kinetic friction between the chair and the floor. 5. A student pulls on a rope attached to a box of books and moves the box down the hall. The student pulls with a force of 185 N at an angle of 25.0˚ above the horizontal. The box has a mass of 35.0 kg and μk between the box and the floor is 0.27. Find the acceleration of the box. 6. A 75 kg kg box slides down a 25.0˚ ramp with an acceleration of 3.602 m/s2. a. Find μk between the box and the ramp. b. What acceleration would a 175 kg box have on this ramp? 7. A box of books weighing 325N moves at a constant velocity across the floor when the box is pushed with a force of 425N exerted downward at an angle of 35.2˚ below the horizontal. Find μk between the box and the floor. 8. The force of air resistance acting on a certain falling object is roughly proportional to the square of the object’s velocity and is directed upward. If the object falls fast enough, will the force of air resistance eventually exceed the weight of the object and cause the object to move upward? Explain.

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