Question 1

A 51-kg woman runs up a flight of stairs in 5.0 s. Her net upward displacement is 5.0 m. Approximately, what average power did the woman exert while she was running?

Accepted Answer

A) 5.0 kW 
B) 1.0 kW 
C) 0.75 kW 
D) 0.50 kW 
E) 0.25 kW 
A) 5.0 kW 
B) 1.0 kW 
C) 0.75 kW 
D) 0.50 kW 
E) 0.25 kW

Question 2

A 12.5-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure.  
-What is the speed of the crate when it arrives at the lower surface?

Accepted Answer

A) 7.7 m/s 
B) 8.6 m/s 
C) 59 m/s 
D) 75 m/s 
E) 98 m/s 
A) 7.7 m/s 
B) 8.6 m/s 
C) 59 m/s 
D) 75 m/s 
E) 98 m/s

Question 3

The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much work is required to stop the car in 10 s?

Accepted Answer

A) zero joules 
B) 8 × 104 J 
C) 8 × 105 J 
D) 8 × 106 J 
E) 8 × 107 J 
A) zero joules 
B) 8 × 104 J 
C) 8 × 105 J 
D) 8 × 106 J 
E) 8 × 107 J

Question 4

Which one of the following statements concerning kinetic energy is true?

Accepted Answer

A) Kinetic energy can be measured in watts. 
B) Kinetic energy is always equal to the potential energy. 
C) Kinetic energy is always positive. 
D) Kinetic energy is a quantitative measure of inertia. 
E) Kinetic energy is directly proportional to velocity. 
A) Kinetic energy can be measured in watts. 
B) Kinetic energy is always equal to the potential energy. 
C) Kinetic energy is always positive. 
D) Kinetic energy is a quantitative measure of inertia. 
E) Kinetic energy is directly proportional to velocity.

Question 5

An engineer is asked to design a playground slide such that the speed a child reaches at the bottom does not exceed 6.0 m/s. Determine the maximum height that the slide can be.

Accepted Answer

A) 1.8 m 
B) 2.9 m 
C) 3.2 m 
D) 4.5 m 
E) 7.4 m 
A) 1.8 m 
B) 2.9 m 
C) 3.2 m 
D) 4.5 m 
E) 7.4 m

Question 6

In which one of the following systems is there a decrease in gravitational potential energy?

Accepted Answer

A) a boy stretches a horizontal spring 
B) a girl jumps down from a bed 
C) a crate rests at the bottom of an inclined plane 
D) a car ascends a steep hill 
E) water is forced upward through a pipe 
A) a boy stretches a horizontal spring 
B) a girl jumps down from a bed 
C) a crate rests at the bottom of an inclined plane 
D) a car ascends a steep hill 
E) water is forced upward through a pipe

Question 7

A car is traveling at 7.0 m/s when the driver applies the brakes. The car moves 1.5 m before it comes to a complete stop. If the car had been moving at 14 m/s, how far would it have continued to move after the brakes were applied? Assume the braking force in both cases is constant and the same.

Accepted Answer

A) 1.5 m 
B) 3.0 m 
C) 4.5 m 
D) 6.0 m 
E) 7.5 m 
A) 1.5 m 
B) 3.0 m 
C) 4.5 m 
D) 6.0 m 
E) 7.5 m

Question 8

Which one of the following is not a unit of energy?

Accepted Answer

A) foot . pound 
B) kilowatt . hour 
C) newton . meter 
D) watt 
E) joule 
A) foot . pound 
B) kilowatt . hour 
C) newton . meter 
D) watt 
E) joule

Question 9

Which one of the following choices is an example of a non-conservative force?

Accepted Answer

A) gravitational force 
B) electrical force 
C) kinetic frictional force 
D) elastic spring force 
A) gravitational force 
B) electrical force 
C) kinetic frictional force 
D) elastic spring force

Question 10

A block of mass m is released from rest at a height R above a horizontal surface. The acceleration due to gravity is g. The block slides along the inside of a frictionless circular hoop of radius R.  
-What is the magnitude of the normal force exerted on the block by the hoop when the block reaches the bottom of the hoop?

Accepted Answer

A) zero newtons 
B) mg2/R 
C) mg 
D) 2mg 
E) 3mg 
A) zero newtons 
B) mg2/R 
C) mg 
D) 2mg 
E) 3mg

Question 11

The force component acting on an object along the displacement varies with the displacement s as shown in the graph. Determine the work done on the object as it travels from s = 0.0 to 12 m.

Accepted Answer

A) 48 J 
B) 66 J 
C) 72 J 
D) 57 J 
E) 81 J 
A) 48 J 
B) 66 J 
C) 72 J 
D) 57 J 
E) 81 J

Question 12

Which one of the following choices is an example of a conservative force?

Accepted Answer

A) tension 
B) normal force 
C) static frictional force 
D) motor propulsion force 
E) elastic spring force 
A) tension 
B) normal force 
C) static frictional force 
D) motor propulsion force 
E) elastic spring force

Question 13

The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much power is required to stop the car in 10 s?

Accepted Answer

A) zero watts 
B) 8 × 104 W 
C) 8 × 105 W 
D) 8 × 106 W 
E) 8 × 107 W 
A) zero watts 
B) 8 × 104 W 
C) 8 × 105 W 
D) 8 × 106 W 
E) 8 × 107 W

Question 14

A concrete block is pulled 7.0 m across a frictionless surface by means of a rope. The tension in the rope is 40 N; and the net work done on the block is 247 J. What angle does the rope make with the horizontal?

Accepted Answer

A) 28° 
B) 41° 
C) 47° 
D) 62° 
E) 88° 
A) 28° 
B) 41° 
C) 47° 
D) 62° 
E) 88°

Question 15

A 325-N force accelerates a 50.0-kg crate from rest along a horizontal frictionless surface for a distance of 20.0 m as shown in the figure.  
-How much work is done on the crate?

Accepted Answer

A) 1.62 × 102 J 
B) 7.70 × 102 J 
C) 3.82 × 103 J 
D) 6.50 × 103 J 
E) 1.50 × 104 J 
A) 1.62 × 102 J 
B) 7.70 × 102 J 
C) 3.82 × 103 J 
D) 6.50 × 103 J 
E) 1.50 × 104 J

Question 16

A motorist driving a 1000-kg car wishes to increase her speed from 20 m/s to 30 m/s in 5 s. Determine the horsepower required to accomplish this increase. Neglect friction.

Accepted Answer

A) 20 hp 
B) 30 hp 
C) 70 hp 
D) 80 hp 
E) 90 hp 
A) 20 hp 
B) 30 hp 
C) 70 hp 
D) 80 hp 
E) 90 hp

Question 17

A 12.5-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure.  
-What minimum coefficient of kinetic friction is required to bring the crate to a stop over a distance of 5.0 m along the lower surface?

Accepted Answer

A) 0.30 
B) 0.32 
C) 0.60 
D) 0.66 
E) 0.76 
A) 0.30 
B) 0.32 
C) 0.60 
D) 0.66 
E) 0.76

Question 18

A 2.0-kg projectile is fired with initial velocity components vox = 30 m/s and voy = 40 m/s from a point on the earth's surface. Neglect any effects due to air resistance.
-How much work was done in firing the projectile?

Accepted Answer

A) 900 J 
B) 1600 J 
C) 2500 J 
D) 4900 J 
E) 9800 J 
A) 900 J 
B) 1600 J 
C) 2500 J 
D) 4900 J 
E) 9800 J

Question 19

The initial velocity of a 4.0-kg box is 11 m/s, due west. After the box slides 4.0 m horizontally, its speed is 1.5 m/s. Determine the magnitude and the direction of the non-conservative force acting on the box as it slides.

Accepted Answer

A) 42 N, due west 
B) 120 N, due east 
C) 31 N, due east 
D) 59 N, due east 
E) 83 N, due west 
A) 42 N, due west 
B) 120 N, due east 
C) 31 N, due east 
D) 59 N, due east 
E) 83 N, due west

Question 20

Two boxes are connected to each other as shown. The system is released from rest and the 1.00-kg box falls through a distance of 1.00 m. The surface of the table is frictionless. What is the kinetic energy of box B just before it reaches the floor?

Accepted Answer

A) 2.45 J 
B) 4.90 J 
C) 9.80 J 
D) 29.4 J 
E) 39.2 J 
A) 2.45 J 
B) 4.90 J 
C) 9.80 J 
D) 29.4 J 
E) 39.2 J

Exam 6: Work and Energy

A 51-kg woman runs up a flight of stairs in 5.0 s. Her net upward displacement is 5.0 m. Approximately, what average power did the woman exert while she was running?

A 12.5-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure. -What is the speed of the crate when it arrives at the lower surface?

The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much work is required to stop the car in 10 s?

Which one of the following statements concerning kinetic energy is true?

An engineer is asked to design a playground slide such that the speed a child reaches at the bottom does not exceed 6.0 m/s. Determine the maximum height that the slide can be.

In which one of the following systems is there a decrease in gravitational potential energy?

A car is traveling at 7.0 m/s when the driver applies the brakes. The car moves 1.5 m before it comes to a complete stop. If the car had been moving at 14 m/s, how far would it have continued to move after the brakes were applied? Assume the braking force in both cases is constant and the same.

Which one of the following is not a unit of energy?

Which one of the following choices is an example of a non-conservative force?

The force component acting on an object along the displacement varies with the displacement s as shown in the graph. Determine the work done on the object as it travels from s = 0.0 to 12 m.

Which one of the following choices is an example of a conservative force?

The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much power is required to stop the car in 10 s?

A concrete block is pulled 7.0 m across a frictionless surface by means of a rope. The tension in the rope is 40 N; and the net work done on the block is 247 J. What angle does the rope make with the horizontal?

A 325-N force accelerates a 50.0-kg crate from rest along a horizontal frictionless surface for a distance of 20.0 m as shown in the figure. -How much work is done on the crate?

A motorist driving a 1000-kg car wishes to increase her speed from 20 m/s to 30 m/s in 5 s. Determine the horsepower required to accomplish this increase. Neglect friction.

A 2.0-kg projectile is fired with initial velocity components vox = 30 m/s and voy = 40 m/s from a point on the earth's surface. Neglect any effects due to air resistance. -How much work was done in firing the projectile?

The initial velocity of a 4.0-kg box is 11 m/s, due west. After the box slides 4.0 m horizontally, its speed is 1.5 m/s. Determine the magnitude and the direction of the non-conservative force acting on the box as it slides.

Two boxes are connected to each other as shown. The system is released from rest and the 1.00-kg box falls through a distance of 1.00 m. The surface of the table is frictionless. What is the kinetic energy of box B just before it reaches the floor?

Introduction and Mathematical Concepts

Kinematics in One Dimension

Kinematics in Two Dimensions

Forces and Newtons Laws of Motion

Dynamics of Uniform Circular Motion

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

Filters

The kinetic energy of a car is 8 × 10⁶ J as it travels along a horizontal road. How much work is required to stop the car in 10 s?

The force component acting on an object along the displacement varies with the displacement s as shown in the graph. Determine the work done on the object as it travels from s= 0.0 to 12 m.

The kinetic energy of a car is 8 × 10⁶ J as it travels along a horizontal road. How much power is required to stop the car in 10 s?