Question 1

Newton's Second Law F = ma. expressed in terms of momentum, reads

Accepted Answer

A)  F = p. 
B)  $\frac { d } { d t }$ F = p. 
C)  F = $\frac { d } { d t }$ p. 
D)  F = m( $\frac { d } { d t }$ p). 
E)  F = p/m. 
A)  F = p. 
B)  $\frac { d } { d t }$ F = p. 
C)  F = $\frac { d } { d t }$ p. 
D)  F = m( $\frac { d } { d t }$ p). 
E)  F = p/m. C

Question 2

A 100-kg cannon is placed on a frozen pond. It fires a 0.50-kg projectile at 20 m/s at an angle of 60o with the surface of the pond. Ignoring friction, the recoil speed of the cannon is

Accepted Answer

A)  0.20 m/s. 
B)  0.12 m/s. 
C)  0.10 m/s. 
D)  0.09 m/s. 
E)  0.05 m/s. 
A)  0.20 m/s. 
B)  0.12 m/s. 
C)  0.10 m/s. 
D)  0.09 m/s. 
E)  0.05 m/s. E

Question 3

The momentum of a single particle is defined as

Accepted Answer

A)  p = m( $\frac { d } { d t }$ v). 
B)  p = m( $\frac { d } { d t }$ a). 
C)  $\boldsymbol { p } = m \left( \int \boldsymbol { v } d t \right)$ 
D)  p = mv. 
E)  p = ma. 
A)  p = m( $\frac { d } { d t }$ v). 
B)  p = m( $\frac { d } { d t }$ a). 
C)  $\boldsymbol { p } = m \left( \int \boldsymbol { v } d t \right)$ 
D)  p = mv. 
E)  p = ma. D

Question 4

A sailboat enthusiast has mounted a battery-operated fan on his boat to provide an air current for the sail. If the fan is pushing the air toward the right, straight on the sail,

Accepted Answer

A)  the boat moves in the same direction as the air pushed by the fan. 
B)  the boat does not move. 
C)  the boat moves in the direction opposite to the air pushed by the fan. 
D)  more information is needed to work out the answer. 
A)  the boat moves in the same direction as the air pushed by the fan. 
B)  the boat does not move. 
C)  the boat moves in the direction opposite to the air pushed by the fan. 
D)  more information is needed to work out the answer.

Question 5

A flowerpot falls from a balcony. Which statement is true during the fall?

Accepted Answer

A)  The impulse received by the pot is constant during the fall. 
B)  The impulse received by the pot is zero. 
C)  The momentum of the pot is conserved. 
D)  The momentum of the pot-Earth system is conserved. 
E)  The momentum of the pot-Earth system is not conserved. 
A)  The impulse received by the pot is constant during the fall. 
B)  The impulse received by the pot is zero. 
C)  The momentum of the pot is conserved. 
D)  The momentum of the pot-Earth system is conserved. 
E)  The momentum of the pot-Earth system is not conserved.

Question 6

After stealing a 20-kg bag of oranges, an 80-kg thief finds himself at rest on a frozen lake. He attaches himself to the bag of oranges with a long rope and pushes himself off from the bag by giving himself a rightward velocity. When the rope runs out

Accepted Answer

A)  the thief and the bag of oranges will move to the right because the thief has a larger mass. 
B)  the thief and the bag of oranges will move to the right because the thief has a larger kinetic energy. 
C)  the thief and the bag will stop. 
D)  the thief and the bag of oranges will move to the left because the thief has a larger mass. 
E)  the thief and the bag of oranges will move to the left because the thief has a larger kinetic energy. 
A)  the thief and the bag of oranges will move to the right because the thief has a larger mass. 
B)  the thief and the bag of oranges will move to the right because the thief has a larger kinetic energy. 
C)  the thief and the bag will stop. 
D)  the thief and the bag of oranges will move to the left because the thief has a larger mass. 
E)  the thief and the bag of oranges will move to the left because the thief has a larger kinetic energy.

Question 7

A fire fighter sprays water horizontally at 10.0 m/s directly at the wall of a house on fire. If 25 kg of water are delivered in 2.5 seconds, the magnitude of the average force on the wall due to water, assuming that after the impact the water falls straight down the wall, is

Accepted Answer

A)  6.25 N. 
B)  62.5 N. 
C)  100 N. 
D)  625 N. 
E)  15.6 kN. 
A)  6.25 N. 
B)  62.5 N. 
C)  100 N. 
D)  625 N. 
E)  15.6 kN.

Question 8

A truck collides head-on with a car. The larger change in momentum magnitude is experienced by

Accepted Answer

A)  the truck. 
B)  the car. 
C)  Both the truck and the car experience the same change in momentum magnitude. 
D)  Both the truck and the car experience no change in momentum magnitude. 
E)  More information is needed to work out the answer. 
A)  the truck. 
B)  the car. 
C)  Both the truck and the car experience the same change in momentum magnitude. 
D)  Both the truck and the car experience no change in momentum magnitude. 
E)  More information is needed to work out the answer.

Question 9

Consider a rocket that attains a given final speed. Any of the following independent modifications in the design of its components will result in a higher final speed except for

Accepted Answer

A)  the use of a fuel with a higher exhaust speed. 
B)  the use of more mass of fuel. 
C)  the reduction in mass of nonfuel components. 
D)  All of the above are true. 
E)  None of the above is true. 
A)  the use of a fuel with a higher exhaust speed. 
B)  the use of more mass of fuel. 
C)  the reduction in mass of nonfuel components. 
D)  All of the above are true. 
E)  None of the above is true.

Question 10

An object's center of mass is located

Accepted Answer

A)  always inside the object. 
B)  always outside the object. 
C)  always at the geometrical center. 
D)  always at the center of symmetry. 
E)  inside or outside the object, depending on how the mass is distributed. 
A)  always inside the object. 
B)  always outside the object. 
C)  always at the geometrical center. 
D)  always at the center of symmetry. 
E)  inside or outside the object, depending on how the mass is distributed.

Question 11

A 540- kg,10-m-long boat is placed perpendicular to a dock. When a 60-kg boy starts walking from the end to the front of the boat, the front of the boat touches the dock. The boy's distance from the dock when the boy reaches the front of the boat is

Accepted Answer

A)  0.0 m. 
B)  0.50 m. 
C)  1.0 m. 
D)  4.5 m. 
E)  5.5 m. 
A)  0.0 m. 
B)  0.50 m. 
C)  1.0 m. 
D)  4.5 m. 
E)  5.5 m.

Question 12

A pole-vaulter has his center of mass 1.00 m above the ground. He starts running from rest, accelerating at 2.5 m/s2, and travels 10.0 m before he begins to use the pole. How high above the ground can the athlete raise his center of mass?

Accepted Answer

A)  1.6 m. 
B)  2.6 m. 
C)  3.6 m. 
D)  None of the above is correct. 
E)  More information is needed to work out the answer. 
A)  1.6 m. 
B)  2.6 m. 
C)  3.6 m. 
D)  None of the above is correct. 
E)  More information is needed to work out the answer.

Question 13

A railroad car of mass 12,000 kg is moving horizontally at 10 m/s. Suddenly it starts to rain, and water accumulates in the railroad car. Which of the following is true?

Accepted Answer

A)  The railroad car slows down because the linear momentum of the rain + car system is conserved. 
B)  The railroad car continues to move at 10 m/s because the rain is falling vertically while the car is moving in a horizontal plane. 
C)  The railroad car continues to move at 10 m/s because the linear momentum of the rain + car system is conserved. 
D)  The railroad car continues to move at 10 m/s because the total energy of the rain + car system is conserved. 
E)  The railroad car speeds up because the potential energy of the rain is converted into kinetic energy for the car. 
A)  The railroad car slows down because the linear momentum of the rain + car system is conserved. 
B)  The railroad car continues to move at 10 m/s because the rain is falling vertically while the car is moving in a horizontal plane. 
C)  The railroad car continues to move at 10 m/s because the linear momentum of the rain + car system is conserved. 
D)  The railroad car continues to move at 10 m/s because the total energy of the rain + car system is conserved. 
E)  The railroad car speeds up because the potential energy of the rain is converted into kinetic energy for the car.

Question 14

The momentum of a system of particles is conserved if

Accepted Answer

A)  there are an even number of particles in the system to allow an integer number of action-reaction pairs. 
B)  the net force on each particle making up the system is zero. 
C)  the momentum of each particle making up the system is conserved. 
D)  no external forces are acting on the system. 
E)  no internal forces are acting on the system. 
A)  there are an even number of particles in the system to allow an integer number of action-reaction pairs. 
B)  the net force on each particle making up the system is zero. 
C)  the momentum of each particle making up the system is conserved. 
D)  no external forces are acting on the system. 
E)  no internal forces are acting on the system.

Question 15

All of the following dimensions are momentum dimensions except for

Accepted Answer

A)  [kilogram][meter]. 
B)  [kilogram][meter]/[second]. 
C)  [kilogram][watt]/[newton]. 
D)  [newton][second]. 
E)  [joule][second]/[meter]. 
A)  [kilogram][meter]. 
B)  [kilogram][meter]/[second]. 
C)  [kilogram][watt]/[newton]. 
D)  [newton][second]. 
E)  [joule][second]/[meter].

Question 16

An arrow of mass 0.50 kg is shot at an angle of 30o with the horizontal. The bow exerts a force of 100 N on the arrow for 0.40 s. The maximum height reached by the arrow assuming no air resistance is

Accepted Answer

A)  8.16 m. 
B)  3.19 km. 
C)  81.6 m. 
D)  245 m. 
E)  327 m. 
A)  8.16 m. 
B)  3.19 km. 
C)  81.6 m. 
D)  245 m. 
E)  327 m.

Question 17

Two identical 1.0-kg toy cars move at 3.0 m/s, one due north and the other due west. The total momentum of the system is

Accepted Answer

A)  0 N.s. 
B)  3.0 N.s, NW. 
C)  4.2 N.s, NW. 
D)  6.0 N.s, NW. 
E)  18.0 N.s, NW. 
A)  0 N.s. 
B)  3.0 N.s, NW. 
C)  4.2 N.s, NW. 
D)  6.0 N.s, NW. 
E)  18.0 N.s, NW.

Question 18

The velocities of three identical masses are shown in the figure here. The velocity of their center of mass is

Accepted Answer

A)  -1.0i - 1.0j m/s. 
B)  -0.33i - 0.33j m/s. 
C)  -1.0i + 6.0j m/s. 
D)  -0.33i + 2.0j m/s. 
E)  0.0 m/s. 
A)  -1.0i - 1.0j m/s. 
B)  -0.33i - 0.33j m/s. 
C)  -1.0i + 6.0j m/s. 
D)  -0.33i + 2.0j m/s. 
E)  0.0 m/s.

Question 19

A 0.20-kg ball, traveling east at 20 m/s, strikes a wall and rebounds at 18 m/s. The change in the ball's momentum is

Accepted Answer

A)  7.6 N.s, west. 
B)  0.4 N.s, west. 
C)  2.0 N.s. 
D)  0.4 N.s, east. 
E)  7.6 N.s, east. 
A)  7.6 N.s, west. 
B)  0.4 N.s, west. 
C)  2.0 N.s. 
D)  0.4 N.s, east. 
E)  7.6 N.s, east.

Question 20

A circular hole of radius R was cut from metallic disk of uniform thickness and radius 2R. The center of mass of the disk with the hole is placed

Accepted Answer

A)  R/2 away from the center of the original metallic disk (no hole). 
B)  R/4 to the right of the center of the original metallic disk (no hole) 
C)  R/4 to the left of the center of the original metallic disk (no hole). 
D)  R/3 to the right of the center of the original metallic disk (no hole). 
E)  R/3 to the left of the center of the original metallic disk (no hole). 
A)  R/2 away from the center of the original metallic disk (no hole). 
B)  R/4 to the right of the center of the original metallic disk (no hole) 
C)  R/4 to the left of the center of the original metallic disk (no hole). 
D)  R/3 to the right of the center of the original metallic disk (no hole). 
E)  R/3 to the left of the center of the original metallic disk (no hole).

Exam 10: Systems of Particles

Newton's Second Law F = ma. expressed in terms of momentum, reads

A 100-kg cannon is placed on a frozen pond. It fires a 0.50-kg projectile at 20 m/s at an angle of 60o with the surface of the pond. Ignoring friction, the recoil speed of the cannon is

The momentum of a single particle is defined as

A sailboat enthusiast has mounted a battery-operated fan on his boat to provide an air current for the sail. If the fan is pushing the air toward the right, straight on the sail,

A flowerpot falls from a balcony. Which statement is true during the fall?

After stealing a 20-kg bag of oranges, an 80-kg thief finds himself at rest on a frozen lake. He attaches himself to the bag of oranges with a long rope and pushes himself off from the bag by giving himself a rightward velocity. When the rope runs out

A fire fighter sprays water horizontally at 10.0 m/s directly at the wall of a house on fire. If 25 kg of water are delivered in 2.5 seconds, the magnitude of the average force on the wall due to water, assuming that after the impact the water falls straight down the wall, is

A truck collides head-on with a car. The larger change in momentum magnitude is experienced by

Consider a rocket that attains a given final speed. Any of the following independent modifications in the design of its components will result in a higher final speed except for

An object's center of mass is located

A 540- kg,10-m-long boat is placed perpendicular to a dock. When a 60-kg boy starts walking from the end to the front of the boat, the front of the boat touches the dock. The boy's distance from the dock when the boy reaches the front of the boat is

A pole-vaulter has his center of mass 1.00 m above the ground. He starts running from rest, accelerating at 2.5 m/s2, and travels 10.0 m before he begins to use the pole. How high above the ground can the athlete raise his center of mass?

A railroad car of mass 12,000 kg is moving horizontally at 10 m/s. Suddenly it starts to rain, and water accumulates in the railroad car. Which of the following is true?

The momentum of a system of particles is conserved if

All of the following dimensions are momentum dimensions except for

An arrow of mass 0.50 kg is shot at an angle of 30o with the horizontal. The bow exerts a force of 100 N on the arrow for 0.40 s. The maximum height reached by the arrow assuming no air resistance is

Two identical 1.0-kg toy cars move at 3.0 m/s, one due north and the other due west. The total momentum of the system is

The velocities of three identical masses are shown in the figure here. The velocity of their center of mass is

A 0.20-kg ball, traveling east at 20 m/s, strikes a wall and rebounds at 18 m/s. The change in the ball's momentum is

A circular hole of radius R was cut from metallic disk of uniform thickness and radius 2R. The center of mass of the disk with the hole is placed

Space, Time, and Mass

Motion Along a Straight Line

Vectors

Motion in Two and Three Dimensions

Newtons Laws of Motion

Further Applications of Newtons Laws

Work and Energy

Conservation of Energy

Gravitation

Collisions

Rotation of a Rigid Body

Dynamics of a Rigid Body

Statics and Elasticity

Oscillations

Waves

Sound

Fluid Mechanics

The Ideal Gas

Heat

Thermodynamics

Electric Force and the Electric Charge

The Electric Field

Gauss Law

Electrostatic Potential and Energy

Capacitors and Dielectrics

Currents and Ohms Law

Direct Current Circuits

Magnetic Force and Field

Charges and Currents in Magnetic Fields

Electromagnetic Induction

Alternating Current Circuits

Electromagnetic Waves

Reflection, Refraction, and Optics

Interference and Diffraction

The Theory of Special Relativity

Quanta of Light

Spectral Lines, Bohrs Theory, and Quantum Mechanics

Quantum Structure of Atoms, Molecules, and Solids

Nuclei

Elementary Particles and Cosmology

Filters

A 100-kg cannon is placed on a frozen pond. It fires a 0.50-kg projectile at 20 m/s at an angle of 60^o with the surface of the pond. Ignoring friction, the recoil speed of the cannon is

A pole-vaulter has his center of mass 1.00 m above the ground. He starts running from rest, accelerating at 2.5 m/s², and travels 10.0 m before he begins to use the pole. How high above the ground can the athlete raise his center of mass?

An arrow of mass 0.50 kg is shot at an angle of 30^o with the horizontal. The bow exerts a force of 100 N on the arrow for 0.40 s. The maximum height reached by the arrow assuming no air resistance is