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Name _________________________________________________________________ Date _________ Per ______ Forces Test Review 1. What is the definition of Fnet? An unbalanced force 2. How do you find Fnet on a flat surface if all four forces are known? Vector addition (subtract opposing forces) 3. How do you find Fnet on an inclined plane? Fnet=Fgsinθ 4. How do you find FN on a flat surface? Same as Fg 5. How do you find FN on an inclined plane? FN=Fgcosθ 6. How do you find Ff when the forces are unbalanced? Use coefficient of friction in the equation Ff=µFN 7. How do you find Ff when the forces are balanced? Same as Fapp 8. How do you find FT when there is more than one tension force (multiple ropes) for a nonmoving object? FT=FN/cosθ then divide by number of ropes 9. State all three laws of motion 10. What is the cause of something to accelerate? A net force 11. What are three things that an unbalanced force can cause an object to do? to start moving, stop moving or change direction 12. A truck is being pulled out of the mud with a rope connected to another truck. The weight of the stuck truck is 25,000N and the ground exerts a 19,000N force on the truck. Frictional force is 800N and the tension force from the towing truck is 6,000N. Draw a free body diagram of the situation. FN = 19,000N FT = 6,000N Ff = 800N Fg = 25,000N 13. What is the tendency of an object to maintain its current state of motion? inertia 14. A car goes forward along a level road at constant velocity. What must the additional force needed to bring the car into equilibrium be? (greater than normal force, less than normal force, or zero) zero…it’s already in equilibrium 15. What is true about an object if a net force is acting on it? It’s accelerating, changing direction, unbalanced 16. A book that weighs of 100N is pushed across a level desk surface at an acceleration of 0.5 m/s2. What net force acts on the book to make it accelerate? 5.1N 17. According to Newton’s second law, when the same force is applied to two objects of different masses, the object with greater mass will experience a less acceleration and the object with less mass will experience more acceleration. 18. Two perpendicular forces, one of 40.0 N directed upward and the second of 55.0 N directed to the right, act simultaneously on an object with a mass of 30.0 kg. What is the magnitude of the resultant acceleration of the object? 2.27 m/s2 19. An airplane with a mass of 2.4 104 kg tows a glider with a mass of 0.95 104 kg. If the airplane propellers provide a net forward thrust of 4.6 104 N, what is the acceleration of the glider? 1.37 m/s2 20. A hammer drives a nail into a piece of wood. Identify an action-reaction pair, and compare the forces exerted by each object. Equal and opposite forces. Hammer is action on nail & nail is reaction on hammer OR nail is action on wood & wood is reaction on nail. 21. A change in the force of gravity acting on an object will affect the object’s weight. 22. In a game of tug-of-war, a rope is pulled to the left with a force of 85 N and to the right with a force of 119 N. What is the magnitude and direction of the net external force on the rope? 34N to the right 23. A 30 kg book is pushed along a desk at a constant speed with a horizontal applied force of 65 N. a. Draw and label a complete free-body diagram identifying all forces acting on the book. FN Ff 30kg Fg Fapp = 65N b. What is the force of friction acting on the book as it slides? 65N c. How much is the normal force? 294N d. Determine the coefficient of kinetic friction between the book and the desk. 0.22 24. A 15 kg flowerpot is tied with a string that goes around each side of the pot as shown. a. Label the free body diagram for the flowerpot. FN FT1 45° FT2 FT3 15kg b. What is the tension in each string? 69.3N Fg 25. A clean up worker is putting debris in a wheelbarrow when a 3-kg tire comes lose and begins rolling down a steep hill 35° to the horizontal. FN a. Draw the free body diagram. Ff 3kg 35° Fg b. What is the normal force? 24.1N c. What is the net force? 16.9N d. What is the acceleration of the wheelbarrow? 5.6 m/s2