3.3. Work, Energy, and Power

What is work done in physics?

Work done is defined as the product of the magnitude of the force and the distance moved by the object in the direction of the force.

What is the unit of work done?

The unit of work done is joules (J).

How is 1 joule defined?

1 joule is the work done when a force of 1 N moves an object 1 meter in the direction of the force.

What is the principle of conservation of energy?

In a closed system, energy cannot be created or destroyed, only transferred from one form to another.

What are the different forms of energy?

Kinetic, gravitational potential, elastic potential, electric potential, sound, internal, electromagnetic, nuclear, and chemical energy.

What is kinetic energy?

Kinetic energy is the energy associated with the motion of an object with mass.

What is the formula for kinetic energy?

Kinetic energy (Ek) is given by the equation Ek = 1/2 mv².

What is gravitational potential energy (GPE)?

Gravitational potential energy is an object's capacity to do work as a result of its position in a gravitational field.

What is the formula for gravitational potential energy?

Gravitational potential energy (Ep) can be calculated using the formula Ep = mgh.

What happens to gravitational potential energy when an object falls?

GPE is converted to kinetic energy as the object falls.

What is power in physics?

Power is a measure of the rate at which energy is transferred or the rate of work done.

What is the formula for power?

Power (P) is defined as P = W/t, where W is work done and t is the time taken.

How is power measured?

Power is measured in watts (W), where 1 watt equals 1 joule per second.

What does the efficiency of a system measure?

Efficiency measures how much energy is conserved as useful energy.

What is the efficiency formula?

Efficiency (%) = (Useful Output Energy / Total Input Energy) × 100.

What effect does the mass of an object have on its speed in free fall?

The mass of an object has no bearing on its final speed in free fall; acceleration due to gravity is the same for all objects.

What is the relationship between kinetic and potential energy in a closed loop system?

Kinetic energy and potential energy exchange back and forth as the object moves up and down within the gravitational field.

What happens to energy in a closed system?

The total energy in a closed system remains constant, though it may change forms.

In what scenario is work done against gravitational force?

When lifting an object, work is done against gravity, resulting in an increase in GPE.

What happens to the work done when lifting an object in a gravitational field?

The work done on the object equals the gravitational potential energy gained.

How is the work done related to the force and distance moved?

Work done is directly proportional to the magnitude of the force applied and the distance moved in the direction of the force.

What is elastic potential energy?

Elastic potential energy is the energy stored as a result of a reversible change in an object's shape.

What is electric potential energy?

Electric potential energy is the energy of charges due to their position in an electric field.

How is efficiency related to energy loss?

Higher efficiency means less energy is wasted as it indicates more useful energy is conserved.

What is internal energy?

Internal energy is the sum of the randomly distributed kinetic and potential energies of the molecules in a substance.

What does electromagnetic energy consist of?

Electromagnetic energy comes from electromagnetic waves stored within oscillating fields.

What is nuclear energy?

Nuclear energy is the energy stored in the nuclei of atoms, released during rearrangement of particles.

What is chemical energy?

Chemical energy is the energy contained in chemical bonds, released when atoms rearrange.

What defines a closed system in the context of energy conservation?

A closed system is one in which energy transfers can occur but no energy enters or leaves the system.

How does work done relate to the energy transfer when lifting an object?

The work done is equal to the energy transferred to gravitational potential energy when lifting an object against gravity.

What happens to kinetic energy at the top of a roller coaster?

At the top of a roller coaster, kinetic energy is at a minimum, while gravitational potential energy is at a maximum.

How do resistive forces affect the power required by a moving object?

If resistive forces are present, power required increases to overcome these forces and maintain constant velocity.

What is the SI base unit for power?

The SI base unit for power is kgm²s⁻³.

Can energy forms be changed?

Yes, energy can be transferred and converted between different forms.

In which form of energy does an object have at rest in a gravitational field?

An object at rest in a gravitational field has gravitational potential energy.

What is the significance of the angle of applied force in work done?

Only the component of force that is parallel to the direction of movement contributes to the work done.