LAW OF CONSERVATION OF MECHANICAL ENERGY COMPUTATION

What is an example of mechanical energy conservation?

• Pendulum swinging back and forth

• Car accelerating on a straight road

• Wind blowing through a field

• Water flowing down a waterfall

Answer explanation

The example of mechanical energy conservation is a pendulum swinging back and forth, where the energy is transferred between potential and kinetic energy without any loss.

Tags

NGSS.MS-PS3-5

How is mechanical energy computed in a system?

• By multiplying the kinetic energy and potential energy of the system.

• By dividing the kinetic energy by the potential energy of the system.

• By adding the kinetic energy and potential energy of the system.

• By subtracting the kinetic energy from the potential energy of the system.

Answer explanation

By adding the kinetic energy and potential energy of the system.

Tags

NGSS.MS-PS3-5

Explain the concept of potential energy in the context of mechanical energy conservation.

• Potential energy is the energy released during an object's motion

• Potential energy is only relevant in non-mechanical systems

• Potential energy is the energy stored in an object due to its position or state, and it plays a crucial role in the conservation of mechanical energy.

• Potential energy is not affected by an object's position

Answer explanation

Potential energy is the energy stored in an object due to its position or state, and it plays a crucial role in the conservation of mechanical energy.

Tags

NGSS.MS-PS3-2

Describe a scenario where kinetic energy is conserved.

• A ball rolling on a frictionless surface.

• A pendulum swinging back and forth

• A car coming to a stop due to friction

• A rocket launching into space

Answer explanation

A ball rolling on a frictionless surface does not experience any external forces that would cause a loss of kinetic energy, thus conserving it.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Calculate the total mechanical energy of a system with potential energy of 50 J and kinetic energy of 30 J.

• 80 J

• 20 J

• 60 J

• 40 J

Answer explanation

The total mechanical energy is the sum of potential and kinetic energy, which is 50 J + 30 J = 80 J. Therefore, the correct answer is 80 J.

Tags

NGSS.MS-PS3-5

In a frictionless system, how does mechanical energy conservation apply?

• Potential energy is converted to kinetic energy.

• Mechanical energy decreases over time.

• Total mechanical energy (kinetic + potential) remains constant.

• Friction increases the total mechanical energy.

Answer explanation

Total mechanical energy (kinetic + potential) remains constant.

Tags

NGSS.MS-PS3-5

Discuss the role of work in the conservation of mechanical energy.

• Work increases the total mechanical energy by converting it into other forms of energy.

• Work is not related to the conservation of mechanical energy.

• Work changes the distribution of kinetic and potential energy, but the total mechanical energy remains constant in the absence of non-conservative forces.

• Conservation of mechanical energy only applies to systems with friction.

Answer explanation

Work changes the distribution of kinetic and potential energy, but the total mechanical energy remains constant in the absence of non-conservative forces.

Tags

NGSS.MS-PS3-5

If a ball is dropped from a height of 10 meters, what is its kinetic energy just before hitting the ground?

• The kinetic energy is maximum just before hitting the ground

• The kinetic energy is zero just before hitting the ground

• The kinetic energy just before hitting the ground cannot be determined without knowing the mass of the ball.

• The kinetic energy is constant throughout the fall

Answer explanation

The kinetic energy just before hitting the ground cannot be determined without knowing the mass of the ball.

Tags

NGSS.MS-PS3-5

Explain the principle of conservation of mechanical energy in a pendulum system.

• The principle of conservation of mechanical energy only applies to linear motion

• The total mechanical energy (kinetic + potential) of a pendulum system remains constant if no external forces are present.

• The potential energy of a pendulum system is always greater than the kinetic energy

• The mechanical energy of a pendulum system decreases over time

Answer explanation

The total mechanical energy (kinetic + potential) of a pendulum system remains constant if no external forces are present.

Tags

NGSS.MS-PS3-5

Calculate the mechanical energy of a moving car with a mass of 1000 kg and a velocity of 20 m/s.

• 100,000 J

• 400,000 J

• 50,000 J

• 200,000 J

Answer explanation

The mechanical energy of the car is calculated using the formula: 0.5 * mass * velocity^2. Substituting the values, we get 0.5 * 1000 * 20^2 = 200,000 J.

Tags

NGSS.MS-PS3-1