Question 1

How much work is done by a person lifting a 2.0-kg object from the bottom of a well at a constant speed of 2.0 m/s for 5.0 s?

Accepted Answer

A) 0.22 kJ 
B) 0.20 kJ 
C) 0.24 kJ 
D) 0.27 kJ 
E) 0.31 kJ 
A) 0.22 kJ 
B) 0.20 kJ 
C) 0.24 kJ 
D) 0.27 kJ 
E) 0.31 kJ B

Question 2

A 4.0-kg block is lowered down a 37° incline a distance of 5.0 m from point A to point B. A horizontal force (F = 10 N) is applied to the block between A and B as shown in the figure. The kinetic energy of the block at A is 10 J and at B it is 20 J. How much work is done on the block by the force of friction between A and B?

Accepted Answer

A) −58 J 
B) −53 J 
C) −68 J 
D) −63 J 
E) −47 J 
A) −58 J 
B) −53 J 
C) −68 J 
D) −63 J 
E) −47 J C

Question 3

If   = 10,   = 15, and α = 130°, determine the scalar product of the two vectors shown. ​   ​

Accepted Answer

A) +96 
B) −96 
C) +51 
D) −51 
E) −35 
A) +96 
B) −96 
C) +51 
D) −51 
E) −35 A

Question 4

Two equal masses are raised at constant velocity by ropes that run over pulleys, as shown below. Mass B is raised twice as fast as mass A. The magnitudes of the forces are FA and FB, while the power supplied is respectively PA and PB. Which statement is correct? ​   ​

Accepted Answer

A) FB = FA; PB = PA. 
B) FB = FA; PB = 2 PA. 
C) FB = 2 FA; PB = PA. 
D) FB = 2 FA; PB = 2 PA. 
E) PA = FA; PB = FB. 
A) FB = FA; PB = PA. 
B) FB = FA; PB = 2 PA. 
C) FB = 2 FA; PB = PA. 
D) FB = 2 FA; PB = 2 PA. 
E) PA = FA; PB = FB.

Question 5

A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would have used at least ____ J of energy.

Accepted Answer

A) 746 
B) 3.43 × 105 
C) 3.73 × 105 
D) 7.46 × 105 
E) 2.61 × 107 
A) 746 
B) 3.43 × 105 
C) 3.73 × 105 
D) 7.46 × 105 
E) 2.61 × 107

Question 6

A block is pushed across a rough horizontal surface from point A to point B by a force (magnitude P = 5.4 N) as shown in the figure. The magnitude of the force of friction acting on the block between A and B is 1.2 N and points A and B are 0.5 m apart. If the kinetic energies of the block at A and B are 4.0 J and 5.6 J, respectively, how much work is done on the block by the force P between A and B?

Accepted Answer

A) 2.7 J 
B) 1.0 J 
C) 2.2 J 
D) 1.6 J 
E) 3.2 J 
A) 2.7 J 
B) 1.0 J 
C) 2.2 J 
D) 1.6 J 
E) 3.2 J

Question 7

Three particles are placed in the xy plane. A 40-g particle is located at (3, 4) m, and a 50-g particle is positioned at (−2, −6) m. Where must a 20-g particle be placed so that the center of mass of this three-particle system is located at the origin?

Accepted Answer

A) (−1, −3) m 
B) (−1, 2) m 
C) (−1, 12) m 
D) (−1, 7) m 
E) (−1, 3) m 
A) (−1, −3) m 
B) (−1, 2) m 
C) (−1, 12) m 
D) (−1, 7) m 
E) (−1, 3) m

Question 8

A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would reach the summit in ____ seconds.

Accepted Answer

A) 1 
B) 460 
C) 500 
D) 1000 
E) 35,000 
A) 1 
B) 460 
C) 500 
D) 1000 
E) 35,000

Question 9

At the instant a 2.0-kg particle has a velocity of 4.0 m/s in the positive x direction, a 3.0-kg particle has a velocity of 5.0 m/s in the positive y direction. What is the speed of the center of mass of the two-particle system?

Accepted Answer

A) 3.8 m/s 
B) 3.4 m/s 
C) 5.0 m/s 
D) 4.4 m/s 
E) 4.6 m/s 
A) 3.8 m/s 
B) 3.4 m/s 
C) 5.0 m/s 
D) 4.4 m/s 
E) 4.6 m/s

Question 10

An object moving along the x axis is acted upon by a force Fx that varies with position as shown. How much work is done by this force as the object moves from x = 2 m to x = 8 m? ​   ​

Accepted Answer

A) −10 J 
B) +10 J 
C) +30 J 
D) −30 J 
E) +40 J 
A) −10 J 
B) +10 J 
C) +30 J 
D) −30 J 
E) +40 J

Question 11

If   ,   , and the angle between   and   (when the two are drawn starting from the same point) is 60°, what is the scalar product of these two vectors?

Accepted Answer

A) −13 
B) +13 
C) +37 
D) −37 
E) 73 
A) −13 
B) +13 
C) +37 
D) −37 
E) 73

Question 12

Three particles are placed in the xy plane. A 30-g particle is located at (3, 4) m, and a 40-g particle is located at (−2, −2) m. Where must a 20-g particle be placed so that the center of mass of the three-particle system is at the origin?

Accepted Answer

A) (−3, −1) m 
B) (+1, +3) m 
C) (+3, −1) m 
D) (−1, −3) m 
E) (−0.5, −2) m 
A) (−3, −1) m 
B) (+1, +3) m 
C) (+3, −1) m 
D) (−1, −3) m 
E) (−0.5, −2) m

Question 13

As a 2.0-kg object moves from   m to   m, the constant resultant force acting on it is equal to   N. If the speed of the object at the initial position is 4.0 m/s, what is its kinetic energy at its final position?

Accepted Answer

A) 62 J 
B) 53 J 
C) 73 J 
D) 86 J 
E) 24 J 
A) 62 J 
B) 53 J 
C) 73 J 
D) 86 J 
E) 24 J

Question 14

Two vectors   and   are given by   and   . The scalar product of   and a third vector   is −16. The scalar product of   and   is +18. The z component of   is 0. What is the magnitude of   ?

Accepted Answer

A) 7.8 
B) 6.4 
C) 3.6 
D) 5.0 
E) 4.8 
A) 7.8 
B) 6.4 
C) 3.6 
D) 5.0 
E) 4.8

Question 15

If the vectors   and   have magnitudes of 10 and 11, respectively, and the scalar product of these two vectors is −100, what is the magnitude of the sum of these two vectors?

Accepted Answer

A) 6.6 
B) 4.6 
C) 8.3 
D) 9.8 
E) 7.6 
A) 6.6 
B) 4.6 
C) 8.3 
D) 9.8 
E) 7.6

Question 16

The only force acting on a 2.0-kg body as it moves along the x axis is given by Fx = (12 − 2.0x) N, where x is in m. The velocity of the body at x = 2.0 m is 5.5   m/s. What is the maximum kinetic energy attained by the body while moving in the +x direction?

Accepted Answer

A) 36 J 
B) 39 J 
C) 43 J 
D) 46 J 
E) 30 J 
A) 36 J 
B) 39 J 
C) 43 J 
D) 46 J 
E) 30 J

Question 17

If the resultant force acting on a 2.0-kg object is equal to   N, what is the change in kinetic energy as the object moves from   m to   m?

Accepted Answer

A) +36 J 
B) +28 J 
C) +32 J 
D) +24 J 
E) +60 J 
A) +36 J 
B) +28 J 
C) +32 J 
D) +24 J 
E) +60 J

Question 18

A 2.0-kg projectile moves from its initial position to a point that is displaced 20 m horizontally and 15 m above its initial position. How much work is done by the gravitational force on the projectile?

Accepted Answer

A) +0.29 kJ 
B) −0.29 kJ 
C) +30 J 
D) −30 J 
E) −50 J 
A) +0.29 kJ 
B) −0.29 kJ 
C) +30 J 
D) −30 J 
E) −50 J

Question 19

A 5.0-kg object is pulled along a horizontal surface at a constant speed by a 15-N force acting 20° above the horizontal. How much work is done by this force as the object moves 6.0 m?

Accepted Answer

A) 78 J 
B) 82 J 
C) 85 J 
D) 74 J 
E) 43 J 
A) 78 J 
B) 82 J 
C) 85 J 
D) 74 J 
E) 43 J

Question 20

A 2.0-kg block slides down a frictionless incline from point A to point B. A force (magnitude P = 3.0 N) acts on the block between A and B, as shown. Points A and B are 2.0 m apart. If the kinetic energy of the block at A is 10 J, what is the kinetic energy of the block at B?

Accepted Answer

A) 27 J 
B) 20 J 
C) 24 J 
D) 17 J 
E) 37 J 
A) 27 J 
B) 20 J 
C) 24 J 
D) 17 J 
E) 37 J

Exam 9: Energy in Nonisolated Systems

How much work is done by a person lifting a 2.0-kg object from the bottom of a well at a constant speed of 2.0 m/s for 5.0 s?

If = 10, = 15, and α = 130°, determine the scalar product of the two vectors shown. ​ ​

Two equal masses are raised at constant velocity by ropes that run over pulleys, as shown below. Mass B is raised twice as fast as mass A. The magnitudes of the forces are FA and FB, while the power supplied is respectively PA and PB. Which statement is correct? ​ ​

A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would have used at least ____ J of energy.

Three particles are placed in the xy plane. A 40-g particle is located at (3, 4) m, and a 50-g particle is positioned at (−2, −6) m. Where must a 20-g particle be placed so that the center of mass of this three-particle system is located at the origin?

A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would reach the summit in ____ seconds.

At the instant a 2.0-kg particle has a velocity of 4.0 m/s in the positive x direction, a 3.0-kg particle has a velocity of 5.0 m/s in the positive y direction. What is the speed of the center of mass of the two-particle system?

An object moving along the x axis is acted upon by a force Fx that varies with position as shown. How much work is done by this force as the object moves from x = 2 m to x = 8 m? ​ ​

If , , and the angle between and (when the two are drawn starting from the same point) is 60°, what is the scalar product of these two vectors?

Three particles are placed in the xy plane. A 30-g particle is located at (3, 4) m, and a 40-g particle is located at (−2, −2) m. Where must a 20-g particle be placed so that the center of mass of the three-particle system is at the origin?

As a 2.0-kg object moves from m to m, the constant resultant force acting on it is equal to N. If the speed of the object at the initial position is 4.0 m/s, what is its kinetic energy at its final position?

Two vectors and are given by and . The scalar product of and a third vector is −16. The scalar product of and is +18. The z component of is 0. What is the magnitude of ?

If the vectors and have magnitudes of 10 and 11, respectively, and the scalar product of these two vectors is −100, what is the magnitude of the sum of these two vectors?

The only force acting on a 2.0-kg body as it moves along the x axis is given by Fx = (12 − 2.0x) N, where x is in m. The velocity of the body at x = 2.0 m is 5.5 m/s. What is the maximum kinetic energy attained by the body while moving in the +x direction?

If the resultant force acting on a 2.0-kg object is equal to N, what is the change in kinetic energy as the object moves from m to m?

A 2.0-kg projectile moves from its initial position to a point that is displaced 20 m horizontally and 15 m above its initial position. How much work is done by the gravitational force on the projectile?

A 5.0-kg object is pulled along a horizontal surface at a constant speed by a 15-N force acting 20° above the horizontal. How much work is done by this force as the object moves 6.0 m?

A 2.0-kg block slides down a frictionless incline from point A to point B. A force (magnitude P = 3.0 N) acts on the block between A and B, as shown. Points A and B are 2.0 m apart. If the kinetic energy of the block at A is 10 J, what is the kinetic energy of the block at B?

Getting Started

One-Dimensional Motion

Vectors

Two- and Three-Dimensional Motion

Newtons Laws of Motion

Applications of Newtons Laws of Motion

Gravity

Conservation of Energy

Systems of Particles and Conservation of Momentum

Collisions

Rotation I: Kinematics and Dynamics

Rotation II: a Conservation Approach

Static Equilibrium, Elasticity, and Fracture

Fluids

Oscillations

Traveling Waves

Superposition and Standing Waves

Temperature, Thermal Expansion, and Gas Laws

Kinetic Theory of Gases

Heat and the First Law of Thermodynamics

Entropy and the Second Law of Thermodynamics

Electric Forces

Electric Fields

Gausss Law

Electric Potential

Capacitors and Batteries

Current and Resistance

Direct Current Dc Circuits

Magnetic Fields and Forces

Gausss Law for Magnetism and Amperes Law

Faradays Law of Induction

Inductors and Ac Circuits

Maxwells Equations and Electromagnetic Waves

Diffraction and Interference

Applications of the Wave Model

Reflection and Images Formed by Reflection

Refraction and Images Formed by Refraction

Relativity

Filters

If = 10, = 15, and α = 130°, determine the scalar product of the two vectors shown.

Two equal masses are raised at constant velocity by ropes that run over pulleys, as shown below. Mass B is raised twice as fast as mass A. The magnitudes of the forces are FA and FB, while the power supplied is respectively PA and PB. Which statement is correct?

An object moving along the x axis is acted upon by a force Fx that varies with position as shown. How much work is done by this force as the object moves from x = 2 m to x = 8 m?