UNIT 1 - Energy Concepts Flashcards

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1
Q

Define work and the equation for it

A

The product of force and distance moved in the direction of the force when the force is constant

Work done = Force x cos(angle) x distance

W=Fcos(angle)X

(Joules)

Equation becomes w=fx if there is no angle or angle is 0

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2
Q

Define energy

A

Ability to do work (Joules)

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3
Q

Is energy and work scalar or vector

A

Both scalar

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4
Q

What is the principle of conservation of energy

A

Energy cannot be created or destroyed, only transferred from one form to another. Energy is a scalar

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5
Q

Equation for kinetic energy

A

E = 1/2mv²

Kinetic energy(J) = 1/2 x mass(kg) x speed²(ms⁻¹)

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6
Q

What is gravitational potential energy

A

The energy possessed by an object due to its position or height above the earth

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7
Q

How to derive equation for gravitational

A

W = fx
F= ma (a = g, gravitational field strength)

W = mgx
Distance = height

gpe = mgh
Gravitational potential energy = mass x gravitational field strength x height

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8
Q

Define kinetic energy

A

Energy possessed by a moving object

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9
Q

Define elastic potential energy

A

Potential energy stored as
a result of deformation of an elastic object.
(Such as the stretching of a spring)

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10
Q

Equations for elastic potential energy?

A

PE = 1/2kx²
or
Pe = 1/2Fx

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11
Q

Equation for spring constant

A

K = f/x

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12
Q

Explain how KE and GPE changes at points when a ball is thrown into the air

A

As its thrown into the air KE decreased and GPE increases, KE>GPE

At some point it then stops, KE has decreased to zero and GPE has reached maximum

It then starts to fall back down, as it falls back down KE increases, GPE decreases
KE<GPE

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13
Q

How to work out energy lost due to friction?

A

KE = GPE + heat + sound
GPE = KE + heat + sound

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14
Q

How to work out force or distance of the energy lost due to friction?

A

Heat + sound = work done

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15
Q

What is power and units

A

The rate of doing work

Watts(W) or Js⁻¹

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16
Q

Equation for power (thats not
Given)

A

P = Fv
Power = force x velocity

17
Q

Equation for efficiency thats not given

A

% efficiency = useful power output/total power output x 100%

18
Q

How can efficiency be represented in diagrams

A

By a sankey diagram
Which are schematic representations of energy transfers in which the width of the arrows used shows the percentage of the total input energy form

19
Q

What are the 9 types of energy

A

Kinetic
Gravitational potential
Elastic potential
Chemical
Electrical
Radiant
Internal
Thermal/heat
Sound

20
Q

Define chemical energy

A

Energy stored in mixtures of chemicals or chemical compounds (coil, oil, gas)

21
Q

Define electrical energy

A

Energy transferred in electrical circuits by the motion of charge carriers such as electrons

22
Q

Define radiant energy

A

The energy carried by all types of electromagnetic waves (xrays, uv, infa-red, etc)

23
Q

Define internal energy

A

Energy possessed by a body due to the random distribution of the kinetic and potential energies of the molecules which make it up

24
Q

Define thermal energy

A

Energy due to the temperature of an object

25
Q

Define sound energy

A

Energy produced by vibrating objects