Chapter 7: Linear Momentum and Collisions - Review Questions

What is the formula for linear momentum?

a) p = mv

b) p = ma

c) p = mv^2

d) p = m/a

a) p = mv

How is Newton's second law of motion expressed in terms of momentum?

a) F_net = Δp/Δt

b) F_net = ma

c) F_net = mv

d) F_net = mΔv

a) F_net = Δp/Δt

What is the SI unit for momentum?

a) kg·m/s

b) N

c) m/s^2

d) kg·m^2/s^2

a) kg·m/s

In the context of momentum, what does the vector nature of momentum imply?

a) Momentum has both magnitude and direction.

b) Momentum is only a scalar quantity.

c) Momentum is independent of direction.

d) Momentum is always positive.

a) Momentum has both magnitude and direction.

Linear momentum is defined as the product of a system's ___ multiplied by its ___.

mass; velocity

Newton's second law in terms of momentum is expressed as F_net = ___ / ___.

Δp; Δt

How does an airbag reduce the force on a car occupant during a collision?

a) By increasing the momentum change

b) By decreasing the momentum change

c) By increasing the time over which the force acts

d) By decreasing the time over which the force acts

c) By increasing the time over which the force acts

What is the ratio of the magnitudes of impulses on two billiard balls striking a wall, one perpendicular and the other at 30 degrees?

a) 1

b) 1.155

c) 0.866

d) 2

b) 1.155

Impulse is defined as the change in ___.

momentum

The formula for impulse is given by Δp = Fnet ___.

Δt

Which of the following best describes an isolated system?

a) A system with no internal forces.

b) A system with no external forces acting on it.

c) A system with constant velocity.

d) A system with increasing mass.

b) A system with no external forces acting on it.

According to Newton's third law, what is the relationship between the forces during a collision?

a) The forces are equal and opposite.

b) The forces are equal and in the same direction.

c) The forces are unequal and opposite.

d) The forces are unequal and in the same direction.

a) The forces are equal and opposite.

In a collision between two cars, what happens to the total momentum of the system?

a) It increases.

b) It decreases.

c) It remains constant.

d) It becomes zero.

c) It remains constant.

How does the conservation of momentum apply to subatomic particles?

a) It does not apply to subatomic particles.

b) It only applies to particles with mass.

c) It applies to all particles, including massless ones.

d) It only applies to particles in motion.

c) It applies to all particles, including massless ones.

An isolated system is defined as one where the net external force is ___.

zero

According to the conservation of momentum, the total momentum before a collision is equal to the total momentum ___.

after

How does the conservation of momentum principle apply to subatomic particles?

The conservation of momentum principle applies to subatomic particles by ensuring that the total momentum of a system of particles remains constant if no external forces act on it. This principle is used to analyze particle interactions and collisions, even for massless particles like photons.

What is the equation for conservation of momentum in a one-dimensional elastic collision?

a) m1v1 + m2v2 = m1v'1 + m2v'2

b) m1v1^2 + m2v2^2 = m1v'1^2 + m2v'2^2

c) m1v1 = m2v2

d) m1v1^2 = m2v2^2

a) m1v1 + m2v2 = m1v'1 + m2v'2

An elastic collision is one that conserves ___.

internal kinetic energy

The sum of the kinetic energies of the objects in a system is called ___.

internal kinetic energy

In a perfectly inelastic collision, what happens to the colliding objects?

a) They bounce off each other

b) They stick together

c) They explode

d) They pass through each other

b) They stick together

Which of the following is conserved in an inelastic collision?

a) Internal kinetic energy

b) Momentum

c) Both internal kinetic energy and momentum

d) Neither internal kinetic energy nor momentum

b) Momentum

What is the coefficient of restitution for a perfectly elastic collision?

a) 0

b) 0.5

c) 1

d) Greater than 1

c) 1

In a perfectly inelastic collision, the objects involved ___ together after the collision.

stick

The conservation of ___ is a key principle in analyzing collisions.

momentum

In the context of two-dimensional collisions, what are point masses?

a) Objects with no mass

b) Objects that cannot rotate or spin

c) Objects with infinite mass

d) Objects that can only move in one direction

b) Objects that cannot rotate or spin

Which equation represents the conservation of momentum along the x-axis for two colliding objects?

a) m1v1 = m1v1' + m2v2'

b) m1v1x = m1v1x' + m2v2x'

c) m1v1y = m1v1y' + m2v2y'

d) m1v1 = m1v1'cosθ1 + m2v2'cosθ2

d) m1v1 = m1v1'cosθ1 + m2v2'cosθ2

What is the angle of separation between two objects after an elastic collision if they have equal mass?

a) 0 degrees

b) 45 degrees

c) 90 degrees

d) 180 degrees

c) 90 degrees

In two-dimensional collisions, the motion is resolved into components along perpendicular axes, typically the ___-axis and ___-axis.

x; y

The equation for conservation of momentum along the y-axis is 0 = m1v1' ___ θ1 + m2v2' ___ θ2.

sin; sin

Why are point masses used in the analysis of two-dimensional collisions?

Point masses are used because they simplify the analysis by eliminating rotational effects, focusing only on translational motion.

How does the conservation of momentum help in determining the final velocities in a two-dimensional collision?

Conservation of momentum provides equations for both x and y components, allowing the calculation of final velocities when initial conditions are known.

What principle explains the propulsion of rockets and jet engines?

a) Newton's First Law of Motion

b) Newton's Second Law of Motion

c) Newton's Third Law of Motion

d) Conservation of Energy

c) Newton's Third Law of Motion

Which factor does NOT affect the acceleration of a rocket?

a) Exhaust velocity

b) Fuel burn rate

c) Mass of the rocket

d) Color of the rocket

d) Color of the rocket

What is the practical limit for exhaust velocity in conventional rocket propulsion systems?

a) 1.0×10^3 m/s

b) 2.5×10^3 m/s

c) 5.0×10^3 m/s

d) 7.5×10^3 m/s

b) 2.5×10^3 m/s

What is the primary reason for using multistage rockets?

a) To reduce the cost of fuel

b) To increase the payload capacity

c) To achieve higher final velocities

d) To improve the aesthetic design

c) To achieve higher final velocities

According to Newton's third law of motion, for every action, there is an equal and opposite ___.

reaction

The acceleration of a rocket is given by the formula a = ve (Δm/Δt) - ___.

g

Explain how Newton's third law of motion applies to rocket propulsion.

Newton's third law of motion states that for every action, there is an equal and opposite reaction. In rocket propulsion, the action is the expulsion of gas out of the rocket engine, and the reaction is the movement of the rocket in the opposite direction.

What are the three major factors that affect the acceleration of a rocket?

The three major factors affecting rocket acceleration are the exhaust velocity of the gases, the rate at which mass is ejected (fuel burn rate), and the mass of the rocket.