1d forces and motion

Transcription

1 Name: ate: 1. car accelerates uniformly from rest to a speed of 10 meters per second in 2 seconds. The acceleration of the car is 4. book weighing 20. newtons slides at constant velocity down a ramp inclined 30. to the horizontal as shown in the accompanying diagram m/sec 2. 5 m/sec m/sec m/sec 2 2. n object near the surface of planet X falls freely from rest and reaches a speed of 12.0 meters per second after it has fallen 14.4 meters. What is the acceleration due to gravity on planet X? m/s m/s m/s m/s 2 3. car is traveling at a constant speed of 14 meters per second along a straight highway. tree and a speed limit sign are beside the highway. s it passes the tree, the car starts to accelerate. The car is accelerated uniformly at 2.0 meters per second 2 until it reaches the speed limit sign, 5.0 seconds later. What is the force of friction between the book and the ramp?. 10. N up the ramp. 17 N up the ramp. 10. N down the ramp. 17 N down the ramp 5. person kicks a 4.0-kilogram door with a 48-newton force causing the door to accelerate at 12 meters per second 2. What is the magnitude of the force exerted by the door on the person?. 48 N. 24 N. 12 N. 4.0 N What is the distance between the tree and the sign? 6. Which combination of three concurrent forces acting on a body could not produce equilibrium?. 10 m. 25 m. 70 m. 95 m. 1 N, 3 N, 5 N. 2 N, 2 N, 2 N. 3 N, 4 N, 5 N. 4 N, 4 N, 5 N 7. If a 30-newton force is required to accelerate a 2-kilogram object at 10 meters per second 2, over a level floor, then the magnitude of the frictional force acting on the object is. 0 N. 10 N. 20 N. 30 N page 1

2 8. The diagram shows a student applying a 10-newton force to slide a piece of wood at constant speed across a horizontal surface. fter the wood is cut in half, one piece is placed on top of the other, as shown newton force and an 8-newton force act concurrently on a box located on a frictionless horizontal surface. Which top-view diagram shows the forces producing the smallest magnitude of accleration of the box?. What is the magnitude of the force, F, required to slide the stacked wood at constant speed across the surface?.. 40 N. 20 N. 10 N. 5.0 N 9. The accompanying diagram shows a child pulling a 50.-kilogram friend on a sled by applying a 300.-newton force on the sled rope at an angle of 40. with the horizontal Equilibrium exists in a system where three forces are acting concurrently on an object. If the system includes a 5.0-newton force due north and a 2.0-newton force due south, the third force must be The vertical component of the 300.-newton force is approximately. 510 N. 230 N. 190 N. 32 N. 7.0 N south. 7.0 N north. 3.0 N south. 3.0 N north 12. 2,400-kilogram car is traveling at a speed of 20. meters per second. ompared to the magnitude of the force required to stop the car in 12 seconds, the magnitude of the force required to stop the car in 6.0 seconds is. half as great. twice as great. the same. four times as great page 2

3 13. The accompanying diagram shows a block on a horizontal frictionless surface newton force acts on the block at an angle of 30. above the horizontal newton horizontal force is needed to keep an object weighing 500. newtons moving at a constant velocity of 2.0 meters per second across a horizontal surface. The magnitude of the frictional force acting on the object is N N. 50. N. 0 N What is the magnitude of force F if it establishes equilibrium? N N N. 187 N newton force directed east and a 5-newton force directed north act concurrently on a point. The resultant of the two forces is 18. different force is applied to each of four 1-kilogram blocks to slide them across a uniform steel surface at constant speed as shown below. In which diagram is the coefficient of friction between the block and steel smallest?... 5 N northeast. 10. N southwest. 7 N northeast. 7 N southwest. 15. Into how many possible components can a single force be resolved?.. an unlimited number. two components. three components. four components at right angles to each other 19. mosquito flying over a highway strikes the windshield of a moving truck. ompared to the magnitude of the force of the truck on the mosquito during the collision, the magnitude of the force of the mosquito on the truck is 16. wooden block is at rest on a horizontal steel surface. If a 10.-newton force applied parallel to the surface is required to set the block in motion, how much force is required to keep the block moving at constant velocity?. less than 10. N. greater than 10. N. 10. N. smaller. larger. the same 20. The magnitude of the force that a baseball bat exerts on a ball is 50. newtons. The magnitude of the force that the ball exerts on the bat is. 5.0 N. 10. N. 50. N. 250 N page 3

4 21. The accompanying diagram shows a granite block being slid at constant speed across a horizontal concrete floor by a force parallel to the floor kilogram skydiver is falling at a constant speed near the surface of Earth. The magnitude of the force of air friction acting on the skydiver is approximately. 0 N. 6 N. 60 N. 600 N Which pair of quantities could be used to determine the coefficient of friction for the granite on the concrete?. mass and speed of the block. mass and normal force on the block. frictional force and speed of the block. frictional force and normal force on the block 22. In which situation is the net force on the object equal to zero? 26. When a 12-newton horizontal force is applied to a box on a horizontal tabletop, the box remains at rest. The force of static friction acting on the box is. 0 N. between 0 N and 12 N. 12 N. greater than 12 N 27. box is pushed toward the right across a classroom floor. The force of friction on the box is directed toward the. a satellite moving at constant speed around Earth in a circular orbit. an automobile braking to a stop. a bicycle moving at constant speed on a straight, level road. a pitched baseball being hit by a bat 23. 1,200-kilogram car traveling at 10. meters per second hits a tree and is brought to rest in 0.10 second. What is the magnitude of the average force acting on the car to bring it to rest? N N N N 24. spring scale reads 20. newtons as it pulls a 5.0-kilogram mass across a table. What is the magnitude of the force exerted by the mass on the spring scale?. left. right. ceiling. floor kilogram mass is moving across a horizontal surface at 5.0 meters per second. What is the magnitude of the net force required to bring the mass to a stop in 8.0 seconds?. 1.0 N. 5.0 N. 25 N. 40. N kilogram red ball is thrown horizontally at a speed of 4 meters per second from a height of 3 meters. 0.4-kilogram green ball is thrown horizontally from the same height at a speed of 8 meters per second. ompared to the time it takes the red ball to reach the ground, the time it takes the green ball to reach the ground is. one-half as great. twice as great. the same. four times as great. 49 N. 20. N. 5.0 N. 4.0 N page 4

5 30. The force required to start an object sliding across a uniform horizontal surface is larger than the force required to keep the object sliding at a constant velocity. The magnitudes of the required forces are different in these situations because the force of kinetic friction 33. The diagram below represents a block at rest on an incline.. is greater than the force of static friction. is less than the force of static friction. increases as the speed of the object relative to the surface increases. decreases as the speed of the object relative to the surface increases Which diagram best represents the forces acting on the block? (italf f = frictional force, F N = normal force, and F w = weight.). 31. Two carts are pushed apart by an expanding spring, as shown in the diagram below.. If the average force on the 1-kilogram cart is 1 newton, what is the average force on the 2-kilogram cart?. 1 N. 0.0 N. 0.5 N. 4 N 32. The diagram below shows a 5.00-kilogram block at rest on a horizontal, frictionless table... Which diagram best represents the force exerted on the block by the table? force of 1 newton is equivalent to 1... kg m s 2. kg m s. kg m 2 s 2. kg 2 m 2 s 2 page 5

6 35. carpenter hits a nail with a hammer. ompared to the magnitude of the force the hammer exerts on the nail, the magnitude of the force the nail exerts on the hammer during contact is. less. greater. the same 36. student is standing in an elevator that is accelerating downward. The force that the student exerts on the floor of the elevator must be. less than the weight of the student when at rest. greater than the weight of the student when at rest 38. Which situation describes an object that has no unbalanced force acting on it?. an apple in free fall. a satellite orbiting Earth. a hockey puck moving at constant velocity acrcoss ice. a laboratory cart moving down a frictionless 30. incline 39. n 8.0-newton block is accelerating down a frictionless ramp inclined at 15 to the horizontal, as shown in the diagram below.. less than the force of the floor on the student. greater than the force of the floor on the student 37. s shown in the diagram below, an open box and its contents have a combined mass of 5.0 kilograms. horizontal force of 15 newtons is required to push the box at a constant speed of 1.5 meters per second across a level surface. What is the magnitude of the net force causing the block s acceleration?. 0 N. 2.1 N. 7.7 N. 8.0 N 40. Four forces act concurrently on a block on a horizontal surface as shown in the diagram below. The inertia of the box and its contents increases if there is an increase in the. speed of the box. mass of the contents of the box. magnitude of the horizontal force applied to the box. coefficient of kinetic friction between the box and the level surface s a result of these forces, the block. moves at constant speed to the right. moves at constant speed to the left. accelerates to the right. accelerates to the left page 6

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