5 Work, Energy, and Power Flashcards

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1
Q

Define work done

A

Force causing a motion multiplied by distance moved in that direction. Energy transferred - energy= capacity to do work

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2
Q

Work done unit

A

Joule - N m.
1J moves 1m in the direction of the force.

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3
Q

Work done at an angle equation?

A

work done W = (Fcosθ) * 𝑥
W=F 𝑥 cosθ

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4
Q

State the principle of conservation of energy

A

The total energy of a closed system remains constant: energy can never be created nor destroyed, only transferred.

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5
Q

List the 9 types of energy

A

Kinetic energy
Gravitational Potential energy
Chemical energy
Elastic Potential energy
Electrical Potential energy
Nuclear energy
Electromagnetic (radiant) energy
Sound energy
Internal (thermal) energy

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6
Q

Define Kinetic energy

A

energy due to motion of an object with mass
Ek=1/2 mv^2

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7
Q

Define Gravitational Potential energy

A

energy of an object due to its position in a gravitational field
Ep=mgh

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8
Q

Define Chemical energy

A

energy contained within chemical bonds between atoms

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9
Q

Define Elastic Potential energy

A

energy stored in an object as a result of reversible change in its shape

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10
Q

Define Electrical Potential energy

A

Energy of electrical charges due to their position in an electric field

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11
Q

Define Nuclear energy

A

energy within the nuclei of atoms

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12
Q

Define Electromagnetic energy

A

Associated with electromagnetic waves, stored within the oscillating electric and magnetic fields

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13
Q

Define Sound energy

A

Energy of mechanical waves due to the movement of atoms

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14
Q

Define Internal (Thermal) energy

A

The sum of the random potential and kinetic energies of atoms in a system

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15
Q

Define power

A

Power is the rate of work done
P=W/t (Js^-1)

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16
Q

Relationship between power and motion?

A

A constant force F moves the car a distance in a time t
Work done=F * 𝑥
P=W/t ∴ =F𝑥/t
Speed of car is 𝑥/t ∴ P=Fv

17
Q

Define efficiency

A

The ratio of useful energy output to the total energy input in a system, expressed as a percentage
efficiency=useful/total *100