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physics > 1.1 > Flashcards

1.1 Flashcards

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1
Q

How is energy transferred?

A

Energy is transferred by heating, by waves, by an electric current,or by a force when it moves an object.

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2
Q

When an object falls and gains speed what happens to the gravitational and kinetic energy store?

A

Gravitational energy decreases and kinetic energy increases.

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3
Q

When a falling object hits the ground without bouncing back, it’s kinetic energy store decreases. Some or all of this energy is transferred to the surroundings . What is it transferred to?

A

The thermal energy store of the surroundings increased and energy is also transferred by sound waves.

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4
Q

Name 4 different ways energy can be transferred?

A

Heating, waves, an electric current or when a force moves an object.

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5
Q

What are 5 energy stores?

A

Chemical energy stores include fuels, foods, or chemicals founds in batteries. The energy is transferred during chemical reactions.

Kinetic energy’s stores describe the energy an object has because it is moving

Gravitational potential energy stores are used to describe the energy stored in an object because of its position, such as an object above the ground

Elastic potential energy stores describe the energy stored in a springy object when you stretch or squash it

Thermal energy stores describe the energy of a substance has because of its temperature

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6
Q

What is the conservation of energy?

A

Energy cannot be created or destroyed. Conservation of energy applies to all energy changes

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7
Q

What is a closed system

A

A closed system is a system in which no energy transfers take place out of or into the energy stores of the system.

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8
Q

What is work done equal to?

A

Energy transferred

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9
Q

What is done on an object when the force makes the object move

A

Work

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10
Q

What is the formula for work done?

A

Work done,w= force applied, F x distanced moved along the line of action of the force, s (metres,)

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11
Q

What is work done to overcome friction transferred as?

A

Work done to overcome friction is transferred as energy to the thermal energy stores of the objects that rub together and to the surroundings

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12
Q

What does the work done when an object moves up and down depend on?

A

How far it is moved vertically (its change of height

It’s weight

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13
Q

What happens to the gravitational potential energy store of an object when it moves up or down

A

Moves up-gravitational potential energy store increases and moves down-gravitational potential energy store decreases

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14
Q

What is the change in the gravitational potential energy store of an object?

A

Change of gravitational potential energy store, joules j = mass,m (kilograms,kg) x gravitational field strength g (Newton’s per kilogram, N/kg x change of height (metres, m)

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15
Q

What is the equation for change in objects gravitational potential energy store

A

Change in objects gravitational potential energy store joules= weight x change of height metres

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16
Q

What is the equation for kinetic energy?

A

Kinetic energy Ek (joules,j) = 1/2 x mass (kg) x speed^2,v^2 (metres per second, m/s)^2

17
Q

What is the formula for elastic potential?

A

Elastic potential energy,E= 1/2 x spring constant, k newtons per mètre) x extension^2 c^2

18
Q

What is useful energy?

A

It is the energy transferred to where it is wanted in the way that it is wanted.

19
Q

What is wasted energy?

A

It is the energy that is not usefully transferred.

20
Q

Where is wasted energy eventually transferred to?

A

The surroundings which become warmer.

21
Q

What happens when energy dissipates? (Spreads out)

A

It gets less and less useful

22
Q

What is the equation for the efficiency of a device?

A

The efficiency of a device = useful energy transferred by the device / total energy supplied to the device (x100)

23
Q

Can energy transfer be more than 100 percent efficient?

A

No

24
Q

Give examples of how machines waste energy?

A

Friction between their moving parts, air resistance, electrical resistance, and noise.

25
Q

What supplies most of the energy you use in your home?

A

Electricity and gas and/ or oil

26
Q

What is power

A

Power Is rate of transfer energy

27
Q

What is the equation for power

A

Power, p (watts,W) = energy transferred to appliance, E (joules,j)/time taken for energy to be transferred seconds,s

28
Q

What is the equation for efficiency of an appliance(power)

A

Efficiency of an appliance = useful power out/total power in (x100)

29
Q

What is the equation for power wasted by an appliance

A

Power wasted = total power in-useful power out

physics (9 decks)

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