Physics Work, Power & Energy Review - Concepts

Impulse is defined as the change in ____.

• velocity

• momentum

• acceleration

• force

Answer explanation

Impulse is defined as the change in momentum, which is the product of mass and velocity. Therefore, the correct answer is momentum, as impulse directly relates to how momentum changes due to applied forces.

Tags

NGSS.HS-PS2-2

What is needed to change an object's momentum?

• A force

• A change in velocity

• A change in mass

• A change in direction

Answer explanation

To change an object's momentum, a force must be applied. Momentum is the product of mass and velocity, and a force causes a change in either or both, thus altering momentum.

Tags

NGSS.HS-PS2-1

If an object experiences an impulse and stops, what is its final momentum?

• Zero

• Equal to the impulse

• Equal to the initial momentum

• Cannot be determined

Answer explanation

When an object experiences an impulse and stops, its final momentum is zero. This is because momentum is conserved, and if the object comes to a complete stop, it has no momentum left.

Tags

NGSS.HS-PS2-2

The law of conservation of momentum states that _____________.

• The total momentum of a closed system remains constant if no external forces act on it.

• Momentum is always conserved in any system, regardless of external forces.

• Momentum can be created or destroyed in a closed system.

• The total momentum of a system is always zero.

Answer explanation

The correct choice accurately reflects the law of conservation of momentum, which states that in a closed system with no external forces, the total momentum remains constant.

Tags

NGSS.HS-PS2-2

Which of Newton’s laws explains how momentum is conserved in all interactions between objects?

• Newton's First Law

• Newton's Second Law

• Newton's Third Law

• Law of Universal Gravitation

Answer explanation

Newton's Third Law states that for every action, there is an equal and opposite reaction. This principle explains how momentum is conserved in interactions, as the forces between objects are equal and opposite, maintaining total momentum.

Tags

NGSS.HS-PS2-2

What quantities are conserved in elastic collisions?

• Momentum and kinetic energy

• Only momentum

• Only kinetic energy

• Neither momentum nor kinetic energy

Answer explanation

In elastic collisions, both momentum and kinetic energy are conserved. This means that the total momentum and total kinetic energy before and after the collision remain constant, making the correct answer 'Momentum and kinetic energy'.

Tags

NGSS.HS-PS2-2

What quantities are conserved in inelastic collisions?

• Momentum only

• Energy only

• Both momentum and energy

• Neither momentum nor energy

Answer explanation

In inelastic collisions, momentum is conserved while kinetic energy is not. This means that the total momentum before and after the collision remains the same, but some energy is transformed into other forms, like heat or sound.

Tags

NGSS.HS-PS2-2

Define the physics quantity of work.

• The product of force and displacement in the direction of the force

• The rate of change of velocity

• The amount of matter in an object

• The force exerted by a magnetic field

Answer explanation

Work is defined as the product of force and displacement in the direction of the force. This means that only the component of force that acts in the direction of movement contributes to the work done.

Is there net work done on an object at rest or moving at a constant velocity?

• Yes, because there is a change in kinetic energy.

• No, because there is no change in kinetic energy.

• Yes, because forces are acting on the object.

• No, because the object is not moving

Answer explanation

No net work is done on an object at rest or moving at constant velocity because there is no change in kinetic energy. Work is only done when there is a change in energy, which does not occur in these scenarios.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

Work is measured in what unit? What base units make up this unit?

• Joule; Newton meter

• Watt; Joule per second

• Pascal; Newton per square meter

• Newton; Kilogram meter per second squared

Answer explanation

Work is measured in Joules, which is defined as a Newton meter. This means that one Joule is the work done when a force of one Newton is applied over a distance of one meter.