P1 Flashcards

1
Q

What are the ways energy can be transferred

A

-By heating
-by waves
-by an electric current
-by a force when it moves an object

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2
Q

What happens to an object when it falls and gains speed

A

Its store of gravitational potential energy decreases and kinetic energy store increases

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3
Q

What ways can energy be transferred

A

Heating, waves, electric current, by moving force

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4
Q

What energy is transferred in a falling object

A

Gravitational potential energy decreases, kinetic potential energy increases

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5
Q

What energy is transferred when an object hits the ground without bouncing

A

Kinetic energy store decreases, most energy transferred to surroundings and thermal energy store of surroundings increases

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6
Q

What is the conservation of energy principle

A

Energy cannot be created or destroyed

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7
Q

Where does conservation of energy apply

A

All energy changes

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8
Q

What is a closed system?

A

A place where no energy is transferred into or out of the system but can be transferred within it

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9
Q

What is work done

A

Energy transferred when an object is moved

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10
Q

Equation involving Force Distance and Work done

A

Work done = Force applied x distance moved from force

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11
Q

What force do you need to lift an object upwards

A

A force Equal to The weight (m x gf) of the object

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12
Q

What happens to gravitational potential energy stores when an object moves upwards

A

increases = work done by lifting force

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13
Q

What happens to gravitational potential energy stores when an object moves down

A

Decreases = to work done by gravity

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14
Q

Equation for change in gravitational energy store

A

Change in GES(J) =W(N) x Change in Height (M)

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15
Q

Equation for kinetic energy store

A

Kinetic energy (J) = 1/2x mass (Kg) x Speed(m/s^2]

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16
Q

Equation for emergy store of stretched elastic spring

A

Elastic potential energy (J) = 1/2x spring constant (N/m) x extension^2 (m^2)

17
Q

What arebthe factors for the amount of kinetic enery in a kinetic energy store

A

Mass and speed

18
Q

What is elastic potential energy?

A

The amount of energy stored in an elastic object when work is done on it

19
Q

What is useful energy

A

Energy in the place we want it and the form we need it

20
Q

What is wasted energy?

A

Energy that is not useful and transferred by an undesired pathway

21
Q

What happens when energy dissipates (spreads out)

A

It gets less and less useful

22
Q

What happens to wasted energy

A

Its eventually transferred to the surroundings which become warmer

23
Q

Why might machines waste energy

A

-Friction between moving parts
-air resistance
-electrical resistance
-noise

24
Q

How can you reduce the problem of friction wasting energy in machines

A

Lubricate the moving parts

25
Q

What is the equation for effiency

A

Efficiency = useful output energy transferred by the device / total input energy supplied to the device

26
Q

What is input energy

A

Energy supplied to the device

27
Q

What is output energy

A

Energy transferred by the device

28
Q

What energy do you use at home

A

Gas, electricity, oil.

29
Q

Why are electrical appliances efficient

A

Because they are designed for a particular purpose so should waste as little energy as possible

30
Q

Examples of everyday electrical appliances

A

-Heating
-lighting
-producing sound and visual images (tv, radio)
-eletrical motors that make things move (toys, blender)