Unit 4: Energy

• Kinetic energy: KE = 1/2mv^2

• Potential energy: PE = mgh

• Work-energy theorem: Wnet = ΔKE = KEf - KEi

• Conservation of mechanical energy: KEi + PEi = KEf + PEf

• Power: P = W/t

• Law of conservation of energy: Energy cannot be created or destroyed, only transferred or transformed.

Work is the transfer of energy that occurs when a force is applied over a distance.

The formula for work is W = Fd, where W is work, F is force, and d is distance.

Work is measured in joules (J).

The formula for work becomes W = Fd cos θ.

Mechanical energy is the sum of kinetic energy and potential energy in a system.

Kinetic energy is the energy of motion and is given by the formula KE = 1/2mv^2, where m is mass and v is velocity.

Potential energy is the energy stored in an object due to its position or configuration and is given by the formula PE = mgh, where m is mass, g is acceleration due to gravity, and h is height.

Yes, mechanical energy is conserved in a closed system, meaning that the total amount of mechanical energy remains constant.

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

The formula for the work-energy theorem is Wnet = ΔKE, where Wnet is the net work done on an object and ΔKE is the change in its kinetic energy.

The sum of an object’s kinetic energy and potential energies is called its total mechanical energy.

The equation Ki + Ui = Kf + Uf holds if no nonconservative forces are doing work. However, if work is done by such forces during the process under investigation, then the equation needs to be modified to account for this work as follows: Ki + Ui + Wother = Kf + Uf.

Power is the rate at which work is done or energy is transferred. It is a scalar quantity and is measured in watts (W).

The formula for power is P = W/t, where P is power, W is work, and t is time.

The SI unit for power is watts (W).

Energy is the ability to do work, while power is the rate at which work is done. The amount of energy used depends on both the power and the time it is used for.

Efficiency is a measure of how much of the input energy is converted into useful output energy.

The efficiency of a device can be calculated using the formula: efficiency = useful output energy / input energy.

Power is also related to efficiency. The higher the power output of a device, the more ene