Question 1

A net force of 25 N is applied for 5.7 s to a 12-kg box initially at rest. What is the speed of the box at the end of the 5.7-s interval?

Accepted Answer

A) 1.8 m/s 
B) 12 m/s 
C) 3.0 m/s 
D) 7.5 m/s 
E) 30 m/s 
A) 1.8 m/s 
B) 12 m/s 
C) 3.0 m/s 
D) 7.5 m/s 
E) 30 m/s

Question 2

With one exception, each of the following units can be used to express mass. What is the exception?

Accepted Answer

A) newton 
B) slug 
C) gram 
D) N•s2/m 
E) kilogram 
A) newton 
B) slug 
C) gram 
D) N•s2/m 
E) kilogram

Question 3

A block is at rest on a rough inclined plane and is connected to an object with the same mass as shown. The rope may be considered massless; and the pulley may be considered frictionless. The coefficient of static friction between the block and the plane is μs; and the coefficient of kinetic friction is μk. 
 
-If the rope were cut between the block and the pulley, what would be the magnitude of the acceleration of the block down the plane?

Accepted Answer

A) g 
B) g - $\mu$k sin $\theta$ 
C) g - $\mu$k cos $\theta$ 
D) g(tan $\theta$ - $\mu$k sin $\theta$) 
E) g(sin $\theta$ - $\mu$k cos $\theta$) 
A) g 
B) g - $\mu$k sin $\theta$ 
C) g - $\mu$k cos $\theta$ 
D) g(tan $\theta$ - $\mu$k sin $\theta$) 
E) g(sin $\theta$ - $\mu$k cos $\theta$)

Question 4

A 2.0-kg object moves in a straight line on a horizontal frictionless surface.
The graph shows the velocity of the object as a function of time. The various equal time intervals are labeled using Roman numerals: I, II, III, IV, and V.   The net force on the object always acts along the line of motion of the object.
-In which section(s) of the graph is the net force changing?

Accepted Answer

A) I and III 
B) II and IV 
C) III 
D) IV 
E) I and V 
A) I and III 
B) II and IV 
C) III 
D) IV 
E) I and V

Question 5

Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line?

Accepted Answer

A) velocity 
B) inertia 
C) acceleration 
D) equilibrium 
E) force 
A) velocity 
B) inertia 
C) acceleration 
D) equilibrium 
E) force

Question 6

The wheels of an automobile are locked as it slides to a stop from an initial speed of 30.0 m/s. If the coefficient of kinetic friction is 0.600 and the road is horizontal, approximately how long does it take the car to stop?

Accepted Answer

A) 4.22 s 
B) 5.10 s 
C) 8.75 s 
D) 10.4 s 
E) 15.3 s 
A) 4.22 s 
B) 5.10 s 
C) 8.75 s 
D) 10.4 s 
E) 15.3 s

Question 7

Under what condition(s) will an object be in equilibrium?

Accepted Answer

A) If the object is either at rest or moving with constant velocity, it is in equilibrium. 
B) If the object is either moving with constant velocity or with constant acceleration, it is in equilibrium. 
C) Only if the object is at rest can it be in equilibrium. 
D) Only if the object is moving with constant velocity can it be in equilibrium. 
E) Only if the object is moving with constant acceleration can it be in equilibrium. 
A) If the object is either at rest or moving with constant velocity, it is in equilibrium. 
B) If the object is either moving with constant velocity or with constant acceleration, it is in equilibrium. 
C) Only if the object is at rest can it be in equilibrium. 
D) Only if the object is moving with constant velocity can it be in equilibrium. 
E) Only if the object is moving with constant acceleration can it be in equilibrium.

Question 8

A block of mass M is held motionless on a frictionless inclined plane by means of a string attached to a vertical wall as shown in the drawing.  
-Assume the plane is not frictionless and the string breaks, what minimum value of the coefficient of static friction, $\mu$s, would prevent the block from sliding down the inclined plane?

Accepted Answer

A) zero 
B) 1 
C) cos $\theta$ 
D) sin $\theta$ 
E) tan $\theta$ 
A) zero 
B) 1 
C) cos $\theta$ 
D) sin $\theta$ 
E) tan $\theta$

Question 9

A certain crane can provide a maximum lifting force of 25 000 N. It hoists a 2000-kg load starting at ground level by applying the maximum force for a 2-second interval; then, it applies just sufficient force to keep the load moving upward at constant speed. Approximately how long does it take to raise the load from ground level to a height of 30 m?

Accepted Answer

A) 2 s 
B) 5 s 
C) 7 s 
D) 9 s 
E) 10 s 
A) 2 s 
B) 5 s 
C) 7 s 
D) 9 s 
E) 10 s

Question 10

Which one of the following statements best explains why the weight of an object of mass m is different on Mars than it is on the Earth?

Accepted Answer

A) The mass of Mars is different from that of Earth. 
B) The masses and radii of Mars and Earth are not the same. 
C) The mass m is further from the Earth's center when it is on Mars. 
D) The constant G is different on Mars. 
E) The mass m will be different on Mars. 
A) The mass of Mars is different from that of Earth. 
B) The masses and radii of Mars and Earth are not the same. 
C) The mass m is further from the Earth's center when it is on Mars. 
D) The constant G is different on Mars. 
E) The mass m will be different on Mars.

Question 11

A 10-kg block is connected to a 40-kg block as shown in the figure. The surface on that the blocks slide is frictionless. A force of 50 N pulls the blocks to the right.  
-What is the magnitude of the acceleration of the 40-kg block?

Accepted Answer

A) 0.5 m/s2 
B) 1 m/s2 
C) 2 m/s2 
D) 4 m/s2 
E) 5 m/s2 
A) 0.5 m/s2 
B) 1 m/s2 
C) 2 m/s2 
D) 4 m/s2 
E) 5 m/s2

Question 12

What is the tension in the horizontal cable?

Accepted Answer

A) 87 N 
B) 150 N 
C) 170 N 
D) 260 N 
E) 300 N 
A) 87 N 
B) 150 N 
C) 170 N 
D) 260 N 
E) 300 N

Question 13

A 4-kg block and a 2-kg block can move on the horizontal frictionless surface. The blocks are accelerated by a +12-N force that pushes the larger block against the smaller one. Determine the force that the 2-kg block exerts on the 4-kg block.

Accepted Answer

A) -4 N 
B) -12 N 
C) 0 N 
D) +4 N 
E) +8 N 
A) -4 N 
B) -12 N 
C) 0 N 
D) +4 N 
E) +8 N

Question 14

A boy pulls a 5.0-kg sled with a rope that makes a 60.0° angle with respect to the horizontal surface of a frozen pond. The boy pulls on the rope with a force of 10.0 N; and the sled moves with constant velocity. What is the coefficient of friction between the sled and the ice?

Accepted Answer

A) 0.09 
B) 0.12 
C) 0.18 
D) 0.06 
E) 0.24 
A) 0.09 
B) 0.12 
C) 0.18 
D) 0.06 
E) 0.24

Question 15

A 71-kg man stands on a bathroom scale in an elevator. What does the scale read if the elevator is ascending with an acceleration of 3.0 m/s2?

Accepted Answer

A) 140 N 
B) 480 N 
C) 690 N 
D) 830 N 
E) 910 N 
A) 140 N 
B) 480 N 
C) 690 N 
D) 830 N 
E) 910 N

Question 16

A 44-kg child steps onto a scale and the scale reads 430 N. What is the magnitude of the normal force acting on the child?

Accepted Answer

A) 44 N 
B) 215 N 
C) 430 N 
D) 645 N 
E) 860 N 
A) 44 N 
B) 215 N 
C) 430 N 
D) 645 N 
E) 860 N

Question 17

In an experiment with a block of wood on an inclined plane, with dimensions shown in the figure, the following observations are made:   (1) If the block is placed on the inclined plane, it remains there at rest. (2) If the block is given a small push, it will accelerate toward the bottom of the incline without any further pushing.
Which one of the following statements is the best conclusion that can be drawn from these observations?

Accepted Answer

A) The coefficient of kinetic friction must be negative. 
B) Both coefficients of friction must be less than 0.25. 
C) Both coefficients of friction must be greater than 0.25. 
D) The coefficient of static friction must be less than the coefficient of kinetic friction. 
E) The coefficient of static friction is greater than 0.25 while the coefficient of kinetic friction is less than 0.25. 
A) The coefficient of kinetic friction must be negative. 
B) Both coefficients of friction must be less than 0.25. 
C) Both coefficients of friction must be greater than 0.25. 
D) The coefficient of static friction must be less than the coefficient of kinetic friction. 
E) The coefficient of static friction is greater than 0.25 while the coefficient of kinetic friction is less than 0.25.

Question 18

Two point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational force between them change?

Accepted Answer

A) The force will be one-third as great. 
B) The force will be one-ninth as great. 
C) The force will be three times as great. 
D) The force will be nine times as great. 
E) It is impossible to determine without knowing the numerical values of m, M, and d. 
A) The force will be one-third as great. 
B) The force will be one-ninth as great. 
C) The force will be three times as great. 
D) The force will be nine times as great. 
E) It is impossible to determine without knowing the numerical values of m, M, and d.

Question 19

A rope connects boat A to boat B. Boat A starts from rest and accelerates to a speed of 9.5 m/s in a time t = 47 s. The mass of boat B is 540 kg. Assuming a constant frictional force of 230 N acts on boat B, what is the magnitude of the tension in the rope that connects the boats during the time that boat A is accelerating?

Accepted Answer

A) 340 N 
B) 1270 N 
C) 230 N 
D) 860 N 
E) 160 N 
A) 340 N 
B) 1270 N 
C) 230 N 
D) 860 N 
E) 160 N

Question 20

Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change?

Accepted Answer

A) The force will be one-third as great. 
B) The force will be one-ninth as great. 
C) The force will be three times as great. 
D) The force will be nine times as great. 
E) It is impossible to determine without knowing the numerical values of m, M, and d. 
A) The force will be one-third as great. 
B) The force will be one-ninth as great. 
C) The force will be three times as great. 
D) The force will be nine times as great. 
E) It is impossible to determine without knowing the numerical values of m, M, and d.

Exam 4: Forces and Newtons Laws of Motion

A net force of 25 N is applied for 5.7 s to a 12-kg box initially at rest. What is the speed of the box at the end of the 5.7-s interval?

With one exception, each of the following units can be used to express mass. What is the exception?

Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line?

The wheels of an automobile are locked as it slides to a stop from an initial speed of 30.0 m/s. If the coefficient of kinetic friction is 0.600 and the road is horizontal, approximately how long does it take the car to stop?

Under what condition(s) will an object be in equilibrium?

Which one of the following statements best explains why the weight of an object of mass m is different on Mars than it is on the Earth?

A 10-kg block is connected to a 40-kg block as shown in the figure. The surface on that the blocks slide is frictionless. A force of 50 N pulls the blocks to the right. -What is the magnitude of the acceleration of the 40-kg block?

What is the tension in the horizontal cable?

A 4-kg block and a 2-kg block can move on the horizontal frictionless surface. The blocks are accelerated by a +12-N force that pushes the larger block against the smaller one. Determine the force that the 2-kg block exerts on the 4-kg block.

A boy pulls a 5.0-kg sled with a rope that makes a 60.0° angle with respect to the horizontal surface of a frozen pond. The boy pulls on the rope with a force of 10.0 N; and the sled moves with constant velocity. What is the coefficient of friction between the sled and the ice?

A 71-kg man stands on a bathroom scale in an elevator. What does the scale read if the elevator is ascending with an acceleration of 3.0 m/s2?

A 44-kg child steps onto a scale and the scale reads 430 N. What is the magnitude of the normal force acting on the child?

Two point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational force between them change?

Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change?

Introduction and Mathematical Concepts

Kinematics in One Dimension

Kinematics in Two Dimensions

Dynamics of Uniform Circular Motion

Work and Energy

Impulse and Momentum

Rotational Kinematics

Rotational Dynamics

Simple Harmonic Motion and Elasticity

Fluids

Temperature and Heat

The Transfer of Heat

The Ideal Gas Law and Kinetic Theory

Thermodynamics

Waves and Sound

The Principle of Linear Superposition and Interference Phenomena

Electric Forces and Electric Fields

Electric Potential Energy and the Electric Potential

Electric Circuits

Magnetic Forces and Magnetic Fields

Electromagnetic Induction

Alternating Current Circuits

Electromagnetic Waves

The Refl Ection of Light: Mirrors

The Refraction of Light: Lenses and Optical Instruments

Interference and the Wave Nature of Light

Special Relativity

Particles and Waves

The Nature of the Atom

Nuclear Physics and Radioactivity

Ionizing Radiation, Nuclear Energy, and Elementary Particles

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A 71-kg man stands on a bathroom scale in an elevator. What does the scale read if the elevator is ascending with an acceleration of 3.0 m/s²?