20 Questions

Sample quiz for Newton's laws of motion and free-body diagrams.

Questions and Answers

- 1.When analyzing dynamics problems, free-body diagrams
- A.
Should always be used

- B.
Are more useful when analyzing horizontal forces than when analyzing vertical forces

- C.
Should include only the forces that are directly responsible for the acceleration

- D.
Should be used only when objects are accelerating

- E.
Only apply to objects in equilibrium

- 2.A force of 12 N acting in a direction [30ºE of S] is equivalent to which of the following pairs of forces acting simultaneously?
- A.
24 N [S], 14 N [E]

- B.
14 N [S], 24 N [E]

- C.
12 N [S], 12 N [E]

- D.
6 N [S], 10 N [E]

- E.
10 N [S], 6 N [E]

- 3.A hockey puck slides along an ice surface shortly after it has left the hockey stick that propelled it. Which of the following free-body diagrams best represents the hockey puck?
- A.
A

- B.
B

- C.
C

- D.
D

- E.
E

- 4.Study the free-body diagram below and choose the statement that best describes the object's motion.
- A.
The object will accelerate north.

- B.
The object will be motionless.

- C.
The object will accelerate northeast.

- D.
The object will travel with uniform motion.

- E.
The object will travel north with a constant velocity.

- 5.Study the free-body diagram below and determine what additional force(s) would be required for the object to achieve uniform motion.
- A.
1 N [W]

- B.
1 N [E]

- C.
2 N [N] and 1 N [W]

- D.
2 N [S] and 1 N [E]

- E.
2 N [S] and 1 N [W]

- 6.The free-body diagram below illustrates the forces acting on a 2.0-kg object as it is being pushed along a horizontal surface. What is the motion of the object?
- A.
Moving at 5.3 m/s2

- B.
Moving at 3.1 m/s

- C.
Moving at 5.3 m/s

- D.
Moving at 3.1 m/s2

- E.
Not moving

- 7.The free-body diagram of a 4.0-kg object is shown below. What additional force must act so that the object has an acceleration of 2.5 m/s
^{2}[W]?- A.
14.0 N [W]

- B.
10.0 N [W]

- C.
8.0 N [W]

- D.
6.0 N [W]

- E.
4.0 N [W]

- 8.Two identical arrows, A and B, are fired with different bows. The bow that fires arrow A exerts twice the average force as the bow that fires arrow B. Compare the accelerations of the two arrows.
- A.
Arrow B will have twice the acceleration of arrow A.

- B.
Arrow A will have twice the acceleration of arrow B.

- C.
Arrow A and arrow B will have the same acceleration.

- D.
Arrow B will have four times the acceleration of arrow A.

- E.
Arrow A will have four times the acceleration of arrow B.

- 9.A hockey puck of mass 150 g is sliding south along the ice and slows at a rate of 1.2 m/s
^{2}. What is the net force acting on the puck?- A.
1.8 x 102 N [N]

- B.
1.8 x 102 N [S]

- C.
1.8 x 101 N [N]

- D.
1.8 x 10-1 N [N]

- E.
1.9 x 10-1 N [S]

- 10.Newton's third law essentially states
- A.
Objects won't move unless pushed

- B.
Acceleration only occurs if there is net force

- C.
The acceleration of an object depends on its mass and the net force acting on it

- D.
Objects which are moving tend to stay moving

- E.
Forces always occur in pairs

- 11.Which of the following observations would be adequately explained by Newton's third law?
- A.
When turning a corner, a passenger in a car is pushed against the door.

- B.
A skater stands on a frictionless pond, tosses her bag in one direction and she accelerates in the opposite direction.

- C.
The normal force on an object is always equal to the force of gravity acting on the same object.

- D.
The friction of a surface causes a sliding object to come to rest.

- E.
When firing a rifle, the force of the rifle on the bullet, is greater than the force of the bullet back on the rifle.

- 12.If the force of gravity that the earth exerts on you is considered to be the action force then, according to Newton's third law, the corresponding reaction force would be the
- A.
Force of gravity you exert on the Earth

- B.
Normal force of the Earth acting upward on you

- C.
Force your feet exert downward on the Earth

- D.
Force you exert on your feet, pressing them against the Earth

- E.
Force of gravity the Earth exerts on everything else

- 13.An object is pushed horizontally at a constant velocity. What can correctly be said about the forces acting on the object?
- A.
The force(s) acting forward is/are greater than the force(s) acting backward.

- B.
The sum of all forces is zero.

- C.
The sum of all forces has a value directed forward.

- D.
The forces acting on the object can be said to be “unbalanced.”

- E.
Newton’s second law best summarizes the effect of the forces acting on the object.

- 14.Which of the following units is equivalent to a newton (N)?
- A.
Kg·m/s2

- B.
G·cm/s

- C.
Kg·s2/m

- D.
Kg·m/s

- E.
Kg·cm/s2

- 15.A 4.0-kg object, A, and a 2.0-kg object, B, are connected with a rope. A force is applied to another rope attached to the 2.0-kg object that pulls both A and B along a horizontal surface. Which of the following statements is true?
- A.
The force that B exerts on A is greater than the force that A exerts on B.

- B.
The force that A exerts on B is greater than the force that B exerts on A.

- C.
The force that B exerts on A is equal to the force that A exerts on B regardless of the motion of the system.

- D.
The force that B exerts on A is equal to the force that A exerts on B provided that the system slides with uniform motion.

- E.
The sum of the applied force and the force that B exerts on A is equal to the force that A exerts on B.

- 16.Three masses are suspended vertically as shown in the diagram below. The system is accelerating upward. What is the relationship among the forces of tension?
- A.
|FT1| = |FT2| = |FT3|

- B.
|FT1| > |FT2| > |FT3|

- C.
|FT1| < |FT2| < |FT3|

- D.
|FT1| > |FT2| < |FT3|

- E.
|FT1| > |FT3| < |FT2|

- 17.The physical quantity, which is the measure of inertia, is
- A.
Density

- B.
Weight

- C.
Force

- D.
Acceleration

- E.
Mass

- 18.Which law is in control of a spaceship which cruises through space at constant speed without using any fuel?
- A.
Newton's first law

- B.
Newton's second law

- C.
Newton's third law

- D.
Both A and B

- E.
All of the above

- 19.An object is hanging by two strings, A and B, anchored to the ceiling as in the diagram below. Each string holds the object in place with a force of 40 N at 30 degrees to the vertical. Determine the force of gravity required to keep the object motionless.
- A.
35 N [down]

- B.
46 N [down]

- C.
69 N [down]

- D.
80 N [down]

- E.
92 N [down]

- 20.Describe the motion of the 2.0 kg mass below in the horizontal plane.
- A.
The object accelerates at 1.5 m/s2 [right]

- B.
The object accelerates at 11 m/s2 [right]

- C.
The object accelerates at 12 m/s2 [right]

- D.
The object accelerates at 13 m/s2 [right]

- E.
The object does not accelerate