20 Questions

Sample test preparation for Forces and Motion unit.

Questions and Answers

- 1.The free-body diagram below represents a 2000-kg elevator. What is the motion of the elevator if the tension in the cable is 1.96 ´ 10
^{4}N? (Assume 3 significant digits.)- A.
The elevator might be accelerating upward.

- B.
The elevator might be accelerating downward.

- C.
The elevator must be at rest.

- D.
The elevator cannot be undergoing uniform motion.

- E.
The elevator must not be accelerating.

- 2.Your "weight" is properly defined as
- A.
The amount of material of which you are composed

- B.
The gravitational force which Earth exerts on you

- C.
The gravitational force you exert on Earth

- D.
The force you exert on a set of bathroom scales

- E.
None of the above

- 3.
- A.
2.2 x 102 N

- B.
1.6 x 102 N

- C.
1.1 x 102 N

- D.
56 N

- E.
28 N

- 4.Which of the following graphs best represents the relationship between the gravitational force,
*F*, that Earth exerts and the mass,*m*, of an object sitting at Earth's surface, that the force is exerted upon?- A.
A

- B.
B

- C.
C

- D.
D

- E.
E

- 5.The gravitational field strength of Earth
- A.
Has a value of exactgly 9.8 N/kg [down] at all locations on its surface

- B.
Is greater at the equator than at the poles

- C.
Is smallest at the peak of Mount Everest, the highest elevation

- D.
Is largest at the deepest spot on the ocean floor

- E.
Is largest at the poles

- 6.If you weighed 112 N on the Moon where
*g*= 1.6 N/kg, how much would you weigh on Earth?- A.
1.1 x 102 N

- B.
1.7 x 104 N

- C.
6.9 x 102 N

- D.
1.1 x 104 N

- E.
6.9 x 103 N

- 7.According to Newton's law of universal gravitation, the gravitational force of attraction between two objects would be
- A.
Half as strong if they're moved twice as far apart

- B.
Twice as strong if they're moved half as far apart

- C.
Four times as strong if they're moved twice as far apart

- D.
Four times as strong if they're moved half as far apart

- E.
Twice as strong if they're moved twice as far apart

- 8.What would the gravitational field strength be on a planet with half Earth's mass and half its radius?
- A.
78.4 N/kg

- B.
39.2 N/kg

- C.
19.6 N/kg

- D.
9.8 N/kg

- E.
4.9 N/kg

- 9.Consider two planets, A and B. Planet A has half the mass and half the radius of planet B. The ratio of
*g*_{A}:*g*_{B}would be- A.
2 : 1

- B.
1 : 2

- C.
4 : 1

- D.
1 : 4

- E.
1 : 1

- 10.Study the force system diagram pictured below and select the factor which would NOT influence the amount of kinetic friction.
- A.
Object's mass

- B.
Coefficient of kinetic friction

- C.
Normal force

- D.
Applied force

- E.
Gravitational field strength

- 11.The coefficient of friction stems from the
- A.
Nature of the two surfaces in contact

- B.
Mass of the object

- C.
Strength of the applied force

- D.
Strength of the normal force

- E.
Strength of the gravitational force

- 12.If the strength of the frictional force is equal to the applied force and oppositely directed, and assuming that all other forces may be ignored, the object
- A.
Must be at rest

- B.
Must be just about to move

- C.
May be at rest or moving at uniform velocity

- D.
Must be accelerating

- E.
Must be slowing down

- 13.A chalk brush sits on a metre stick as pictured in the diagram. As one end of the metre stick is elevated, the chalk brush eventually begins to slide. Why?
- A.
The coefficient of friction changes.

- B.
The gravitational force on the brush changes.

- C.
The normal force on the brush changes.

- D.
The gravitational force begins to act along the metre stick.

- E.
An applied force is created.

- 14.A 425-g model rocket is accelerated upward at 86 m/s
^{2}by its engine. What is the value of the force exerted by the engine on the rocket?- A.
41 N [up]

- B.
41 N [down]

- C.
37 N [up]

- D.
32 N [up]

- E.
32 N [down]

- 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 provided that the system slides with uniform motion.

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

- 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.A 1.5-kg cart is pulled with a force of 7.3 N at an angle of 40° above the horizontal. If a kinetic friction force of 3.2 N acts against the motion, the cart’s acceleration along the horizontal surface will be
- A.
1.0 m/s2

- B.
1.6 m/s2

- C.
2.4 m/s2

- D.
2.7 m/s2

- E.
5.0 m/s2

- 17.A 1.8-kg object is pulled along the floor with a force of 7.0 N acting horizontally. If the object accelerates at 2.4 m/s
^{2}, how much kinetic friction is acting?- A.
30 N

- B.
11 N

- C.
8.3 N

- D.
7.8 N

- E.
2.7 N

- 18.Which of the following statements concerning friction is true?
- A.
The frictional force always acts oppositely to the applied force.

- B.
For two given surfaces, the coefficient of static friction is generally greater than the coefficient of kinetic friction.

- C.
Friction is a force which is unavoidable and serves no practical purpose.

- D.
Two very highly-polished surfaces in contact with one another will have very little friction between them.

- E.
Friction always acts in the direction of motion.

- 19.If all other forces can be ignored and the strength of the frictional force is greater than the applied force and oppositely directed, the object
- A.
Could be speeding up or slowing down

- B.
Must be speeding up

- C.
Must be slowing down

- D.
Could be moving with uniform motion

- E.
Could be stopped

- 20.The free-body diagram of a block being pushed up a rough ramp is best represented by
- A.
A

- B.
B

- C.
C

- D.
D

- E.
E