Friday, October 18, 2024

Physics Chapter 5: Work, Energy and Power

PHYSICS DEFINITION:

Joule: Work done when a force of 1N moves a distance of 1 m in the direction of the force.

Principle of Conservation of Energy: Energy cannot be created or destroyed. It can only be changed from one form to another.

Power: Power of a device is the rate at which it does work per unit of time.

Watt: 1 W is 1 J per second.

 

PHYSICS KEYWORD LIST:

Energy: Calculated quantity that is conserved during any change; that which is transferred when a force does work.

Gravitational Potential Energy (GPE): Energy a body has due to its position in a gravitational field.

 

PHYSICS CHAPTER WISE SUMMARY:

The work done W when a force F moves through a displacement s in the direction of the force:

W = Fs or W = Fs Cos angle (angle between force and displacement)

A joule is defined as the work done (or energy transferred) when a force of 1N moves a distance of 1 m in the direction of the force.

When an object of mass m rises through a height h, its gravitational potential energy increases by an amount: GPE = mgh.

The kinetic energy of a body of mass m moving at speed v is: KE = ½ mv^2.

The principle of conservation of energy states that, for a closed system, energy can be transferred to other forms but the total amount of energy remains constant.

The efficiency of a device or system is determined using the equation: Efficiency = (Useful output energy / Total input energy) x 100%.

Power is the rate at which work is done (or energy transferred): P = W/t and P = Fv.

A watt is defined as a rate of transfer of energy 1 J per second.

 

PHYSICS IMPORTANT NOTES:

Work done = force x distance (W = Fd)

Work done = energy transferred

1 Joule = 1N x 1 m = 1 Nm

Work done = Fd Cos angle

GPE = w x h = mgh

Kinetic Energy = 0.5 x mass x speed ^2 (KE = 1/2 mv^2)

Efficiency = (Useful output energy / Total input energy) x 100 %

Power = Work done / Time (P = W/t)

Power = Force x velocity (P = Fs)

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