Question 1

A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The gravitational force is directed

Accepted Answer

A)  parallel to the plane in the same direction as the movement of the block. 
B)  parallel to the plane in the opposite direction as the movement of the block 
C)  perpendicular to the plane. 
D)  toward the center of the Earth. 
E)  toward the center of mass of the block. 
A)  parallel to the plane in the same direction as the movement of the block. 
B)  parallel to the plane in the opposite direction as the movement of the block 
C)  perpendicular to the plane. 
D)  toward the center of the Earth. 
E)  toward the center of mass of the block.

Question 2

A block lies on a smooth inclined plane tilted at an angle of 35° to the horizontal.
(a) Draw the free-body diagram for the block.
(b) Determine the block's acceleration as it slides down the inclined plane.
(c) If the block started from rest 8.5 m up the incline from its base, determine the block's speed when it reaches the bottom of the incline.
(d) How long did it take the block to reach the bottom of the inclined plane?

Accepted Answer

(a)The block is acted on by th

Question 3

Mass is a measure of how difficult it is to change the velocity of an object.

Accepted Answer

A) True 
 B)False

Question 4

What does the word "normal" mean in the phrase "normal force"?

Accepted Answer

A)  the force that is usually exerted by a surface 
B)  the total force exerted by a surface 
C)  the component of the force exerted by a surface parallel to the surface 
D)  the component of the force exerted by a surface perpendicular to the surface 
E)  the force is due to contact between two objects. 
A)  the force that is usually exerted by a surface 
B)  the total force exerted by a surface 
C)  the component of the force exerted by a surface parallel to the surface 
D)  the component of the force exerted by a surface perpendicular to the surface 
E)  the force is due to contact between two objects.

Question 5

FIGURE 5-4  
-The free-body diagram of an 8.00 kg object is shown in Figure 5-4. What is Newton's Second Law for this object?

Accepted Answer

A)  (6.0 N sin 28° - 5.0 N sin 22°)   + (6.0 N cos 28° + 5.0 N cos 22°)   = (8.00 kg)   
B)  (6.0 N cos 28° + 5.0 N cos 22°)   + (6.0 N sin 28° + 5.0 N sin 22°)   = (8.00 kg)   
C)  (6.0 N cos 28° - 5.0 N sin 22°)   + (6.0 N sin 28° + 5.0 N cos 22°)   = (8.00 kg)   
D)  (6.0 N cos 28° - 5.0 N cos 22°)   + (6.0 N sin 28° + 5.0 N sin 22°)   = (8.00 kg)   
E)  (6.0 N cos 28° + 5.0 N sin 22°)   i + (6.0 N sin 28° - 5.0 N cos 22°)   = (8.00 kg)   
A)  (6.0 N sin 28° - 5.0 N sin 22°)   + (6.0 N cos 28° + 5.0 N cos 22°)   = (8.00 kg)   
B)  (6.0 N cos 28° + 5.0 N cos 22°)   + (6.0 N sin 28° + 5.0 N sin 22°)   = (8.00 kg)   
C)  (6.0 N cos 28° - 5.0 N sin 22°)   + (6.0 N sin 28° + 5.0 N cos 22°)   = (8.00 kg)   
D)  (6.0 N cos 28° - 5.0 N cos 22°)   + (6.0 N sin 28° + 5.0 N sin 22°)   = (8.00 kg)   
E)  (6.0 N cos 28° + 5.0 N sin 22°)   i + (6.0 N sin 28° - 5.0 N cos 22°)   = (8.00 kg)

Question 6

A 40.0-kg crate is being lowered by means of a rope. Its downward acceleration is 2.00 m/s2. What is the force exerted by the rope on the crate?

Accepted Answer

A)  40.0 N 
B)  80.0 N 
C)  232 N 
D)  312 N 
E)  472 N 
A)  40.0 N 
B)  80.0 N 
C)  232 N 
D)  312 N 
E)  472 N

Question 7

When a parachutist jumps from an airplane, he eventually reaches a constant speed, called the terminal velocity. This means that

Accepted Answer

A)  the acceleration is equal to g. 
B)  the force of air resistance is equal to zero. 
C)  the effect of gravity has died down. 
D)  the effect of gravity increases as he becomes closer to the ground. 
E)  the force of air resistance is equal to the weight of the parachutist. 
A)  the acceleration is equal to g. 
B)  the force of air resistance is equal to zero. 
C)  the effect of gravity has died down. 
D)  the effect of gravity increases as he becomes closer to the ground. 
E)  the force of air resistance is equal to the weight of the parachutist.

Question 8

FIGURE 5-2  
-The two forces indicated in Figure 5-2 act on a 3.00-kg object. What is the acceleration of the object?

Accepted Answer

A)  (1.67 m/s2)   - (0.333 m/s2)   
B)  (5.00 m/s2)   + (1.00 m/s2)   
C)  (1.67 m/s2)   + (2.333 m/s2)   
D)  (15.0 m/s2)   + (3.00 m/s2)   
E)  (1.67 m/s2)   + (0.333 m/s2)   
A)  (1.67 m/s2)   - (0.333 m/s2)   
B)  (5.00 m/s2)   + (1.00 m/s2)   
C)  (1.67 m/s2)   + (2.333 m/s2)   
D)  (15.0 m/s2)   + (3.00 m/s2)   
E)  (1.67 m/s2)   + (0.333 m/s2)

Question 9

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg mass, which pushes against the other two masses. What is the contact force between the 3.0-kg mass and the 2.0-kg mass?

Accepted Answer

A)  0 N 
B)  10 N 
C)  25 N 
D)  40 N 
E)  50 N 
A)  0 N 
B)  10 N 
C)  25 N 
D)  40 N 
E)  50 N

Question 10

A force of 120 N is applied to an object whose mass is 30 kg. The object's acceleration is

Accepted Answer

A)  3600 m/s2. 
B)  150 m/s2. 
C)  4.0 m/s2 
D)  2.0 m/s2. 
E)  0.25 m/s2. 
A)  3600 m/s2. 
B)  150 m/s2. 
C)  4.0 m/s2 
D)  2.0 m/s2. 
E)  0.25 m/s2.

Question 11

An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the x-axis, the second is 75 N along a direction making a counterclockwise angle of 150° with the x-axis. What is the direction of the third force, measured counterclockwise from the x-axis?

Accepted Answer

A)  128° 
B)  182° 
C)  226° 
D)  255° 
E)  262° 
A)  128° 
B)  182° 
C)  226° 
D)  255° 
E)  262°

Question 12

An object of weight W is in free-fall close to the surface of Earth. What is the force that the object exerts on Earth?

Accepted Answer

A)  a force greater than W 
B)  a force less than W 
C)  a force equal to W 
D)  no force at all 
E)  cannot be determined without additional information 
A)  a force greater than W 
B)  a force less than W 
C)  a force equal to W 
D)  no force at all 
E)  cannot be determined without additional information

Question 13

The mass of a proton is 1.7 × 10-27 kg. What is the weight of 6.0 × 1023 protons?

Accepted Answer

Question 14

A 120-kg mass rests on a horizontal surface. What is the magnitude of the normal force exerted by the surface on the mass?

Accepted Answer

The answer of A 120-kg mass rests on a horizontal...

Question 15

A 4.00-kg block slides down a frictionless inclined plane with an acceleration 3.00 m/s2. What is the angle of the incline above horizontal?

Accepted Answer

A)  35.3° 
B)  45.2° 
C)  17.8° 
D)  23.6° 
E)  53.7° 
A)  35.3° 
B)  45.2° 
C)  17.8° 
D)  23.6° 
E)  53.7°

Question 16

A 1200-kg car is pulling a 500-kg trailer along level ground. Friction is negligible. The car accelerates with an acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer?

Accepted Answer

A)  550 N 
B)  600 N 
C)  650 N 
D)  700 N 
E)  750 N 
A)  550 N 
B)  600 N 
C)  650 N 
D)  700 N 
E)  750 N

Question 17

A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How large is the contact force between the two boxes?

Accepted Answer

A)  12 N 
B)  20 N 
C)  24 N 
D)  32 N 
E)  0 N 
A)  12 N 
B)  20 N 
C)  24 N 
D)  32 N 
E)  0 N

Question 18

Two objects have masses m and 5m, respectively. They both are placed side by side on a frictionless inclined plane and allowed to slide down from rest.

Accepted Answer

A)  It takes the lighter object 5 times longer to reach the bottom of the incline than the heavier. 
B)  It takes the lighter object 10 times longer to reach the bottom of the incline than the heavier. 
C)  It takes the heavier object 5 times longer to reach the bottom of the incline than the lighter. 
D)  It takes the heavier object 10 times longer to reach the bottom of the incline than the lighter. 
E)  The two objects reach the bottom of the incline at the same time. 
A)  It takes the lighter object 5 times longer to reach the bottom of the incline than the heavier. 
B)  It takes the lighter object 10 times longer to reach the bottom of the incline than the heavier. 
C)  It takes the heavier object 5 times longer to reach the bottom of the incline than the lighter. 
D)  It takes the heavier object 10 times longer to reach the bottom of the incline than the lighter. 
E)  The two objects reach the bottom of the incline at the same time.

Question 19

An ant walks down the surface of a ball. If the ant begins to slip when the normal force is less than one-third of the ant's weight, at what angle, measured from the top of the ball, does the ant begin to slip?

Accepted Answer

A)  70.5° 
B)  19.5° 
C)  55.0° 
D)  18.4° 
E)  35.2° 
A)  70.5° 
B)  19.5° 
C)  55.0° 
D)  18.4° 
E)  35.2°

Question 20

A 10.0-kg picture is held in place by two wires, one hanging at 50.0° to the left of the vertical and the other at 45.0° to the right of the vertical. What is the tension in the second wire?

Accepted Answer

A)  71.8 N 
B)  75.4 N 
C)  98.1 N 
D)  69.4 N 
E)  23.8 N 
A)  71.8 N 
B)  75.4 N 
C)  98.1 N 
D)  69.4 N 
E)  23.8 N

Exam 5: Newtons Laws of Motion

A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The gravitational force is directed

Mass is a measure of how difficult it is to change the velocity of an object.

What does the word "normal" mean in the phrase "normal force"?

FIGURE 5-4 -The free-body diagram of an 8.00 kg object is shown in Figure 5-4. What is Newton's Second Law for this object?

A 40.0-kg crate is being lowered by means of a rope. Its downward acceleration is 2.00 m/s2. What is the force exerted by the rope on the crate?

When a parachutist jumps from an airplane, he eventually reaches a constant speed, called the terminal velocity. This means that

FIGURE 5-2 -The two forces indicated in Figure 5-2 act on a 3.00-kg object. What is the acceleration of the object?

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg mass, which pushes against the other two masses. What is the contact force between the 3.0-kg mass and the 2.0-kg mass?

A force of 120 N is applied to an object whose mass is 30 kg. The object's acceleration is

An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the x-axis, the second is 75 N along a direction making a counterclockwise angle of 150° with the x-axis. What is the direction of the third force, measured counterclockwise from the x-axis?

An object of weight W is in free-fall close to the surface of Earth. What is the force that the object exerts on Earth?

The mass of a proton is 1.7 × 10-27 kg. What is the weight of 6.0 × 1023 protons?

A 120-kg mass rests on a horizontal surface. What is the magnitude of the normal force exerted by the surface on the mass?

A 4.00-kg block slides down a frictionless inclined plane with an acceleration 3.00 m/s2. What is the angle of the incline above horizontal?

A 1200-kg car is pulling a 500-kg trailer along level ground. Friction is negligible. The car accelerates with an acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer?

A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How large is the contact force between the two boxes?

Two objects have masses m and 5m, respectively. They both are placed side by side on a frictionless inclined plane and allowed to slide down from rest.

An ant walks down the surface of a ball. If the ant begins to slip when the normal force is less than one-third of the ant's weight, at what angle, measured from the top of the ball, does the ant begin to slip?

A 10.0-kg picture is held in place by two wires, one hanging at 50.0° to the left of the vertical and the other at 45.0° to the right of the vertical. What is the tension in the second wire?

Introduction to Physics

One-Dimensional Kinematics

Vectors in Physics

Two-Dimensional Kinematics

Applications of Newtons Laws

Work and Kinetic Energy

Potential Energy and Conservation of Energy

Linear Momentum and Collisions

Rotational Kinematics and Energy

Rotational Dynamics and Static Equilibrium

Gravity

Oscillations About Equilibrium

Waves and Sound

Fluids

Temperature and Heat

Phases and Phase Changes

The Laws of Thermodynamics

Electric Charges, Forces, and Fields

Electric Potential and Electric Potential Energy

Electric Current and Direct-Current Circuits

Magnetism

Magnetic Flux and Faradays Law of Induction

Alternating-Current Circuits

Electromagnetic Waves

Geometrical Optics

Optical Instruments

Physical Optics: Interference and Diffraction

Relativity

Quantum Physics

Atomic Physics

Nuclear Physics and Nuclear Radiation

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A 40.0-kg crate is being lowered by means of a rope. Its downward acceleration is 2.00 m/s². What is the force exerted by the rope on the crate?

The mass of a proton is 1.7 × 10^-27 kg. What is the weight of 6.0 × 10²³ protons?

A 4.00-kg block slides down a frictionless inclined plane with an acceleration 3.00 m/s². What is the angle of the incline above horizontal?

A 1200-kg car is pulling a 500-kg trailer along level ground. Friction is negligible. The car accelerates with an acceleration of 1.3 m/s². What is the force exerted by the car on the trailer?