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Physics IGCSE > Chapter #6 & #8 > Flashcards

Chapter #6 & #8 Flashcards

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1
Q

What is the definition of energy?

A

Quantity that must be changed or transferred to make something happen.

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2
Q

How does a person running a race use energy stores and transfers?

A
  • At the start of the race, the runner’s muscles are STORES of chemical energy.
  • As runner starts moving, chemical energy is TRASFERRED to kinetic and thermal energy.
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3
Q

What are the types of energy? (9)

A
  • Kinetic energy (k.e.)
  • Gravitational energy (g.p.e.)
  • Chemical energy
  • Nuclear energy
  • Elastic energy
  • Internal energy
  • Thermal energy
  • Electrical energy
  • Mechanical (such as sound)
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4
Q

What is the definition of kinetic energy?

A

The energy store of a moving object

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5
Q

What is the definition gravitational potential energy (g.p.e.)? + an example.

A

Energy store of an object raised up against the force of gravity.
Ex. When a ball is thrown, the g.p.e. is largest at the top (and the k.e. is largest right before the ball hits the ground.)

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6
Q

What is the definition of chemical energy?

A

Energy stored in bonds between atoms that can be released when chemical reactions happen.

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7
Q

What is the definition of nuclear energy?

A

Energy stored in the nucleus of atoms.

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8
Q

What is the definition of elastic potential energy?

A

Energy stored in the changed shape of an object.

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9
Q

What is the definition of internal energy?

A

The energy of an object; the total kinetic energies of its particles.

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10
Q

What is the definition of thermal energy?

A

The energy transferred from a hotter place to a colder place because of the temp. difference between them.

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11
Q

What energies are energy stores? (7)

A
  • Kinetic energy (k.e.)
  • Gravitational potential energy (g.p.e)
  • Elastic (strain) energy.
  • Nuclear energy
  • Internal energy
  • Electrostatic energy
  • Chemical energy
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12
Q

How is energy transferred?

A

It is transferred from one store to another.

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13
Q

What is an event (with energy)?

A

Something that happens or takes place, often at a specific time and place.

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14
Q

What is a process?

A

A series of actions or steps, often taking place over a long period of time.

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15
Q

What is the definition of Principle of conservation of energy?

A

Energy cannot be created or destroyed; it can only be stored or transferred.

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16
Q

What are the two most wasted energy?

A

Heat and sound

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17
Q

What are the two main ways heat energy is wasted?

A
  • When fuels are burned
  • Because of friction (when moving things or driving a car ect. and friction generates heat.
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18
Q

What are the main ways sound energy is wasted?

A
  • Noisy machinery
  • Loud cars
    But, even loud sounds contain little energy so there is not much to be gained (in energy) by reducing it.
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19
Q

What is the definition of efficiency.

A

The fraction (or percentage) of energy that is usefully transferred.

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20
Q

What is the definition of lubricant?

A

Usually a liquid, it allows two surfaces to slide past each other more easily.

21
Q

What is the definition of dissipated?

A

Energy that is spread out and not useful (wasted).

22
Q

What is the equation for efficiency percentage?

A

useful energy output / total energy input x 100

23
Q

What is the equation for efficiency?

A

useful energy output / total energy input.

24
Q

What does an objects g.p.e. depend on?

A
  • Its height above the ground => the higher the object, the greater its g.p.e.
  • Its weight => the heavier the object, the greater force needed to lift it, hence the greater its g.p.e.
25
Q

What is the value of gravity?

A

10N (9.8N)

26
Q

What is the equation for ‘change in g.p.e.’?

A

weight x change in height
mg x change h

27
Q

How do you make use of an object’s k.e.

A

By slowing it down.
e.x. moving air turns a wind turbine. This slows down air, reducing its k.e. The energy extracted can be used to turn a generator to produce electricity.

28
Q

What two factors does k.e. depend on?

A
  • The object’s mass => the greater the mass the greater its k.e.
  • the objects speed => the greater the speed the greater its k.e.
29
Q

What is the formula for motional k.e.?

A

1/2 x mass x speed ^2

Ek = 1/2 mv^2

30
Q

If you know the g.p.e. and k.e. at any point of a ball being thrown, what is the total energy?

A

g.p.e. + k.e. = total energy

31
Q

What is the unit for work done?

A

Joules

32
Q

What is the unit for power?

A

Watts

33
Q

What does ‘work done’ depend on?

A
  • The size of the force => the greater the force, the more work is done.
  • Distance moved in the direction of the force => the further it moves the more work is done.
34
Q

How can ‘power’ be increased?

A
  • Power can be increased by increasing the work done at any given time.
  • Power can be in increased by reducing the time in which the same work is done.
35
Q

work energy more less

When it moves an object, a smaller force does _____ work than a bigger force.

A

When it moves an object, a smaller force does more work than a bigger force.

36
Q

work energy more less

The greater the distance an object is moved by the force, the ____ work it does.

A

The greater the distance an object is moved by the force, the more work it does.

37
Q

work energy more less

Power is the rate at which _____ is transferred.

A

Power is the rate at which energy is transferred.

38
Q

work energy more less

Power is the rate at which ____ is done

A

Power is the rate at which work is done.

39
Q

work energy more less

The amount of work done is the amount of ___ transferred.

A

The amount of work done is the amount of energy transferred.

40
Q

The work done vertically upwards is =

A

the g.p.e.

41
Q

How much joules is 1 calorie?

A

4.18 joules

42
Q

how do you calculate the distance when you have ‘work done’, ‘time’, and ‘force’?

A

d = W/F

43
Q

What are the different ways that energy can be transferred?

A
  • By force
  • By heating
  • By radiation
  • By electrical current
44
Q

How do you transfer energy by force?

A
  • Force is provided when we provide kinetic energy (by providing force).
  • When we lift an object (g.p.e.)
  • When energy is transferred from one object to another by means of force, we say the force is doing work.
45
Q

How do you transfer energy by heat?

A

From a hot object to its cooler surroudings.

46
Q

How do you transfer energy by radiation?

A

Light reaches us from the sun. Some of the energy is transferred as infrared and ultraviolet radiation.

47
Q

How is energy transferred by electrical current?

A

Electrical current is a convenient way of transferring energy from place to place.

48
Q

What is an explanation of how energy is transferred through electrical current?

A

An electric current transfers energy from the chemical energy store of a flashlight battery to the internal energy of a bulb.

Physics IGCSE (13 decks)

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