Mechanical Energy Concepts

What is the formula for kinetic energy?

• KE = 0.5 * m * v^2

• KE = m * v^2

• KE = m + v

• KE = 0.5 * m * v

Answer explanation

The formula for kinetic energy is KE = 0.5 * m * v^2, where m represents mass and v represents velocity.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

State the law of conservation of mechanical energy.

• Mechanical energy can be created or destroyed in an isolated system

• Mechanical energy is directly proportional to the velocity of an object

• Only non-conservative forces affect the total mechanical energy in a system

• Total mechanical energy in an isolated system remains constant if only conservative forces are acting.

Answer explanation

Total mechanical energy in an isolated system remains constant if only conservative forces are acting.

Explain the work-energy theorem.

• The work-energy theorem states that energy is conserved in a system.

• The work-energy theorem states that the work done on an object is equal to the force applied to it.

• The work-energy theorem states that the work done on an object is equal to its potential energy.

• The work-energy theorem states that the work done on an object is equal to the change in its kinetic energy.

Answer explanation

The work-energy theorem states that the work done on an object is equal to the change in its kinetic energy.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

Define potential energy.

• Potential energy is the energy of motion

• Potential energy is the energy stored in chemical bonds

• Potential energy is the energy of sound waves

• Potential energy is the energy an object has due to its position relative to other objects.

Answer explanation

Potential energy is the energy an object has due to its position relative to other objects.

Tags

NGSS.HS-PS2-4

A 2 kg object is moving with a speed of 3 m/s. What is its kinetic energy?

• 15 J

• 6 J

• 9 J

• 12 J

Answer explanation

The kinetic energy of an object is calculated using the formula KE = 0.5 * m * v^2. Substituting the values, KE = 0.5 * 2 kg * (3 m/s)^2 = 9 J. Therefore, the kinetic energy of the object is 9 J.

If a system has only potential energy, what can you say about its kinetic energy?

• The kinetic energy of the system is infinite.

• The kinetic energy of the system is constant.

• The kinetic energy of the system is zero.

• The kinetic energy of the system is always positive.

Answer explanation

If a system has only potential energy, then its kinetic energy is zero because the two forms of energy are mutually exclusive in the system.

How does mechanical energy remain constant in a system?

• By ensuring no external work is done on the system and no energy is lost due to non-conservative forces.

• By allowing energy to escape the system

• By increasing the system's mass

• By introducing friction into the system

Answer explanation

By ensuring no external work is done on the system and no energy is lost due to non-conservative forces.

Tags

NGSS.HS-PS2-3

Give an example of a situation where potential energy is converted into kinetic energy.

• Airplane taking off from a runway

• Swinging pendulum at its highest point

• Roller coaster car going down a hill

• Bouncing ball on the ground

Answer explanation

The correct choice is the roller coaster car going down a hill, where potential energy is converted into kinetic energy as the car descends.

Tags

NGSS.HS-PS3-3

What is the unit of measurement for energy?

• Meter

• Newton

• Gram

• Joule

Answer explanation

The unit of measurement for energy is Joule. It is a derived unit of energy in the International System of Units (SI).

How is work related to energy?

• Work is the absence of energy in a system.

• Work is the transfer of energy from one form to another or from one object to another.

• Work is the consumption of energy by an object.

• Work is the creation of energy out of nothing.

Answer explanation

Work is the transfer of energy from one form to another or from one object to another.

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-3