statement or answers the qu ircle the correct answer. For questions requiring an extended mathematical response, you must show a correct numerical setup (show mathematical work). Your answer must include a Instructions: correct unit (when appropriate). Numeric solutions should be rounded to the correct number of significant figures. Some questions may require the use of the 2006 Edition Reference Tables for Physical Setting/Physics. Each question is worth ten points. Level I represent conceptually simple, single-step questions. Level II represents conceptually advanced, double-step questions. Level III represents conceptually challenging, multi- step questions. Level I When the net force on an object is zero, we say that the two forces are: A. balanced B. unbalanced C. gross D. cancelled out If you are pushing a box toward your friend with a force of 20 N, and your friend is pushing the box toward you with a force of 30 N, what will happen to the box? A. The box will move toward your friend with a force of 10 N. B. The box will move toward you with a force of 10 N. C. The box will move toward your friend with a force of 50 N. D. The box will move toward you with a force of 50 N. 3. A 5g block is being dragged across a floor by a constant force of 100 N. The coefficient of kinetic friction is 0.3. Find the acceleration of the block. 4. It takes a 50 N horizontal force to pull a 20 kg object along the ground at a constant velocity. What is the coefficient of kinetic friction? 5. A 10 kg box is motionless on the floor. If the coefficient of static friction is 0.4 and the coefficient of kinetic friction is 0.3 (between the box and the floor), find the force required to start the block in motion. 6. A wagon is pulled at a constant velocity by a force of 100 N at an angle of 30" above the horizontal. Find the frictional force acting on the block. Level II 7. A 50 kg box is pulled across a surface by a force of 100 N. A constant force of friction of 25 N acts against the object. Find the objects acceleration. 8. A girl pushes a 2kg snow shovel at a uniform velocity across a sidewalk. If the handle of the shovel is inclined at 55 to the horizontal and she pushes along the handle with a force of 100 N, what is the force of friction? What is the coefficient of kinetic friction? Level III 9. A 200 kg block, on a VERY rough surface, is being pulled/pushed by two people, one on each end. The first person is pulling with a force of 20 N at an angle of 40" above the ground, while the other person is pushing with a 30 N force at an angle of 50" above the ground. Find the normal force on the block. 10. A 2 kg block of wood is sliding across a frictionless surface at a speed of 10 m/s. Suddenly, it hits a shaggy carpet, where the coefficient of kinetic friction is unknown. If the carpet stops the block in 3 seconds, find the missing coefficient. How would this answer have differed if the mass of the block was 8 kg? 1,000,000 kg