Force-Friction-Vectors Review TEACHER ANSWER KEY … · 2010-11-13 · Force-Friction-Vectors...

Force-Friction-Vectors Review TEACHER ANSWER KEY November 12, 2004

1 1. A 150.-newton force, F1, and a 200.-newton force, F2, are applied simultaneously to the same

point on a large crate resting on a frictionless, horizontal surface. Which diagram shows the forces positioned to give the crate the greatest acceleration?

No Explanation Available.

1 2. As an angle between a force and level ground decreased from 60 degrees to 30 degrees, the vertical component of the force

1. decreases 3. remains the same

2. increases


1 3. Forces F1 and F2 act concurrently on point P, as shown in the diagram.

The equilibrant of F1 and F2 is

Page 1 of 20Force-Friction-Vectors Review

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1. 14 N southwest 3. 20. N southwest

2. 14 N southeast 4. 20. N southeast



3 4. The 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.o with the horizontal.



1. 510 N 3. 190 N

2. 230 N 4. 32 N

4 5. A 6-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 acceleration of the box?



3 6. A 5-newton force directed east and a 5-newton force directed north act concurrently on a point. The resultant of the two forces is

1. 5 N northeast 3. 7 N northeast

2. 10. N southwest 4. 7 N southwest



1 7. Into how many possible components can a single force be resolved?

1. an unlimited number 3. three components

2. two components 4. four components at right angles to each other

3 8. In the following diagram, a force, F, is applied to the handle of a lawnmower inclined at angle to the ground. The magnitude of the horizontal component of force F depends on



4 9. An astronaut weights 500 newtons on Earth and 25 newtons on asteroid X. The acceleration due to gravity on asteroid X is approximately

1. 1 m/s2 3. 0.2 m/s2

2. 2 m/s2 4. 0.5 m/s2



4 10. Two students push on a sled. One pushes with a force of 30. newtons east and the other exerts a force of 40. newtons south, as shown in the accompanying top-view diagram. Which vector best represents the resultant of these two forces?



3 11. A boat heads directly eastward across a river at 12 meters per second. If the current in the river is flowing at 5.0 meters per second due south, what is the magnitude of the boat's resultant velocity?



1. 7.0 m/s 3. 13 m/s

2. 8.5 m/s 4. 17 m/s


4 12. Which statement explains why a book resting on a table is in equilibrium?

1. There is a net force acting downward on the book.

3. The acceleration due to gravity is 9.8 m/s^2 for both the book and the table.

2. The weight of the book equals the weight of the table.

4. The weight of the book and the table's upward force on the book are equal in magnitude, but opposite in direction.


1 13. Which combination of concurrent forces could not produce equilibrium?

1. 10. N, 20. N, and 50. N 3. 30. N, 40. N, and 50. N

2. 20. N, 30. N, and 50. N 4. 40. N, 40. N, and 50. N


3 14. The handle of a lawn roller is held at 45 degrees from the horizontal. A force, F, of 28.0 newtons is applied to the handle as the roller is pushed across a level lawn, as shown in the diagram. What is the magnitude of the force moving the roller forward?



1. 7.00 N 3. 19.8 N

2. 14.0 N 4. 39.0 N


4 15. A skier starting from rest skis straight down a slope 50. meters long in 5.0 seconds. What is the magnitude of the acceleration of the skier?

1. 20. m/s2 3. 5.0 m/s2

2. 9.8 m/s2 4. 4.0 m/s2

3 16. In the accompanying diagram, a box is on a frictionless horizontal surface with forces F1 and

F2 acting as shown.

If the magnitude of F1 is greater than the magnitude of F2, then the box is

1. moving at constant speed in the direction of F1

3. accelerating in the direction of F1

2. moving at constant speed in the direction of F2

4. accelerating in the direction of F2



2 17. Which two graphs represent the motion of an object on which the net force is zero?

3 18. The accompanying table lists the coefficients of kinetic friction for four materials sliding over steel. A 10.-kilogram block of each of these materials is pulled horizontally across a steel floor at constant velocity. Which block requires the smallest applied force to keep it moving at constant velocity?

1. aluminum 3. copper

2. brass 4. steel



3 19. 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

1. 5.0 N 3. 50. N

2. 10. N 4. 250 N

2 20. What is an essential characteristic of an object in equilibrium?

1. zero velocity 3. zero potential energy

2. zero acceleration 4. zero kinetic energy

4 21. The diagram shows a granite block being slid at constant speed across a horizontal concrete floor by a force parallel to the floor. Which pair of quantities could be used to determine the coefficient of friction for the granite on the concrete?



1. mass and speed of the block 3. frictional force and speed of the block

2. mass and normal force on the block 4. frictional force and normal force on the block

2 22. A 70.-kilogram astronaut has a weight of 560 newtons on the surface of the planet Alpha. What is the acceleration due to gravity on planet Alpha?

1. 0.0 m/s2 3. 9.8 m/s2

2. 8.0 m/s2 4. 80. m/s2

2 23. The diagram shows a horizontal 8.0-newton force applied to a 4.0-kilogram block on a frictionless table. What is the magnitude of the block's acceleration?



1. 0.50 m/s2 3. 9.8 m/s2

2. 2.0 m/s2 4. 32 m/s2

4 24. A force vector was resolved into two perpendicular components, F1 and F2, as shown in the

diagram. Which vector best represents the original force?



4 25. A 60-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

1. 0 N 3. 60 N

2. 6 N 4. 600 N

3 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

1. 0 N 3. 12 N

2. between 0 N and 12 N 4. greater than 12 N

4 27. A 1.5-kilogram lab cart is accelerated uniformly from rest to a speed of 2.0 meters per second in 0.50 second. What is the magnitude of the force producing this acceleration?

1. 0.70 N 3. 3.0 N

2. 1.5 N 4. 6.0 N

1 28. Which person has the greatest inertia?

1. a 110-kg wrestler resting on a mat 3. a 70-kg long-distance runner traveling at 5 m/s

2. a 90-kg man walking at 2 m/s 4. a 50-kg girl sprinting at 10 m/s



2 29. Which graph best represents the motion of an object that is not in equilibrium as it travels along a straight line?

4 30. A net force of 25 newtons is applied horizontally to a 10.-kilogram block resting on a table. What is the magnitude of the acceleration of the block?

1. 0.0 m/s2 3. 0.40 m/s2

2. 0.26 m/s2 4. 2.5 m/s2



2 31. In the accompanying diagram, the upward drag force acting on a parachute is equal in magnitude but opposite in direction to the weight of the parachutist and equipment. As a result of the forces shown, the parachutist may be moving

1. downward with decreasing speed 3. upward with decreasing speed

2. downward at constant speed 4. upward with constant acceleration



3 32. A ball having mass m is struck by a bat having mass 9 m. Compared to the magnitude of the force exerted by the bat on the ball, the magnitude of the force exerted by the ball on the bat is

1. less 3. the same

2. greater

1 33. Two students are pushing a car. What should be the angle of each student's arms with respect to the flat ground to maximize the horizontal component of the force?

1. 0o 3. 45o

2. 30o 4. 90o



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