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Intro Physics (811) NAME: __________________________________ Friction Quiz Block: ______ Date: ___________________ Matching: ___ ___ ___ ___ ___ ___ ___ ___ (8 points – 1 points each) Newton's First Law A) change in velocity over time Newton's Second Law B) total combination of all forces Newton's Third Law C) F = m · a weight D) the motion of an object will stay the same if nothing happens to it net force E) the force of gravity on an object air resistance F) maximum speed for something falling through air terminal velocity G) if you push something, you are also pushed with the same force acceleration H) force that acts against something falling Multiple Choice: Choose the one best answer to the following questions. (10 points – 2 points each) For 9-11: Hector pushes a box with 48 N of force at a constant 4.0 m/s across a floor. 9. What is the net force on the box? a. 48 N b. 192 W c. 4.8 kg d. zero 10. What is the force of friction on the box? a. 48 N b. 192 N c. 12 N d. zero 11. What type of friction is acting on the box? a. static b. potential c. kinetic d. super-duper For 12-14: Lysa leans with 18 N of horizontal (sideways) force on a desk that weighs 100 N. 12. The static friction between the desk and the floor is up to 16 Newtons. Does the desk move? a. yes, it weighs less b. yes, Lysa's force is c. no, it weighs more d. no, the friction is less than the friction more than the friction than Lysa is pushing than Lysa's leaning 13. If the floor were carpeted and the static friction was up to 20 N, would the desk move then? Lysa's force and the desk's weight are still the same. a. yes, it still weighs b. yes, the friction is c. no, it weighs more d. no, Lysa's force is less than the friction less than Lysa's leaning than Lysa is pushing less than the friction 14. If the desk moves and Lysa stops leaning on it. What kind of friction will stop it from moving far? a. static b. potential c. kinetic d. esoteric Short Answer: Explain clearly and fully. Use the back for more room. (2 points) 15. Give one example of friction being good and helpful, and one example of friction being unhelpful and wasteful. Use your book or ask around.