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Physics P2 > P2 b > Flashcards

P2 b Flashcards

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1
Q

What affects your braking distance

A

Your thinking and braking distance

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2
Q

What affects your thinking time

A

Your reaction time and how fast your going the faster you go the more ground will be covered before reactions take place

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3
Q

What factors affect braking distance

A

How fast your going, the mass of the vehicle a heavier vehicle takes longer to stop. How good your brakes are and how good the grip of the tyres is .

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4
Q

What affects a tires grip

A

Road surface weather conditions and tyre conditions

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5
Q

How do you calculate an objects momentum

A

Mass x Velocity

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6
Q

What happens to momentum after an incident

A

The same momentum is present the total momentum after is the same as before

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7
Q

What happens when a force acts on an object

A

It causes a change in momentum

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8
Q

How can you calculate the force

A 
           Time
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9
Q

What does a larger force mean

A

A faster change of momentum

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10
Q

Why do cars have airbags and such?

A

To extend the time the change in momentum occurs over in order to reduce the force acting on the body

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11
Q

What are examples of safety mechanisms in cars

A

Crumple zones, these increase the time taken for the car to stop
Seat belts stretch slightly increasing the time for the wearer to stop
Air bags slow you down more gradually

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12
Q

What is work

A

It is when a force moves an object and energy is transferred this means work is done

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13
Q

What is power

A

Is the rate of doing work it is calculated by the work done divided by a given time

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14
Q

What is power measured in

A

Watts or joules 1 watt = 1 joule of energy transferred per second
Watts are the same as joules per second

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15
Q

What do all moving objects have

A

Kinetic energy

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16
Q

How to calculate kinetic energy

A

1/2 x mass x velocity squared

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17
Q

What is gravitational potential energy

A

It is the potential energy an object holds mainly affected by its height as that can vary

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18
Q

How do you calculate G.P.E

A

Mass x gravitational field strength x height

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19
Q

What is the principle of conservation of energy

A

Energy can never be created nor destroyed.

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20
Q

When an object falls the kinetic energy gained is equal to

A

The gravitational potential energy lost

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21
Q

What is a problem assuming that kinetic energy gained = gravitational potential energy lost

A

It doesn’t account for other factors such as heat or sound

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22
Q

What happens to unstable nuclei

A

They decay this is random

23
Q

What are the three types of ionising radiation

A

Alpha, short range, weak penetrating
Beta, medium range, medium penetrating
Gamma, long range, highly penetrating

24
Q

What does ionising radiation mean

A

They cause the ionising of atoms or loosing of an electron

25
Q

How does alpha radiation ionise

A

It has a large positive charge when it passes close to an atom it pulls an negatively charged electron out of orbit

26
Q

How does beta radiation ionise

A

It is negatively charged so pushes electrons out of orbit

27
Q

How is gamma radiation ionising

A

The transfer energy to electrons if the electron gains enough energy it can break free

28
Q

What are alpha particles

A

Helium nuclei

Big heavy slow moving positive charge. Paper stops it

29
Q

What are beta particles

A

Electrons emitted from a nucleus

Fast and small negative charge, moderately ionising but stopped by aluminium .

30
Q

What happens when a beta particle is emitted

A

A neutron turns into a proton in the nucleus

31
Q

What is a gamma rays

A

Electromagnetic radiation weakly ionising only stopped by thick lead

32
Q

What is nuclear fission

A

The splitting up of atoms

33
Q

How to start a chain reaction

A

A slow moving neutron is fired at an isotope of uranium. Th neutron is absorbed by the nucleus it becomes unstable and causes it to split

34
Q

How are chain reCtions controlled

A

Placed in a moderator to slow down the neutrons I.e water this creates a steady rate of nuclear fission. Control rods made of boron limit fission by absorbing excess neutrons

35
Q

What is nuclear fusion

A

The joining of two smaller nuclei to make a larger one. This usually happens inside stars and requires extreme pressure and heat

36
Q

Why doesn’t nuclear fusion happen at lower pressures and temperatures

A

Due to electrostatic repulsion of protons

37
Q

Why is a fusion reactor hard to build

A

Most materials are vaporised at the temperature so you have to contain hot hydrogen in a magnetic field instead of physical container

38
Q

What is background radiation

A

Low level radiation that around all the time

39
Q

Where does background radiation come from

A

It comes from natural unstable isotopes radiation from space know as cosmic rays and radiation due to human activity I.e nuclear fallout

40
Q

What is half life

A

The time taken for half the undeclared nuclei to decay

41
Q

What is the radioactivity of an isotope measured in

A

Becquerel s 1Bq is 1 decay per second

42
Q

How to measure half life from a graph

A

Measure the background radiation count first and subtract it from the isotope count. Then divide that by two and find this point on the graph across and down to time

43
Q

What are some uses of radioactive decay

A

Smoke detectors
Sterilisation of food
Trackers and thickness gauges
Treating cancer

44
Q

How is alpha radiation used in smoke debtors

A

A weak source of alpha is placed in a smoke detector close to two electrodes. The source causes ionisation and a current flows. If there is a fire then the smoke will absorb the radiation causing the current to stop and the alarm to trigger

45
Q

How is food sterilised

A

Exposing it to high doses of gamma rays will kill all microbes. This is called irradiation this can be used for medical equipment too

46
Q

How does a thickness gauge work

A

Beta radiation is used in thickness control. You fire beta at the object and place a detector on the other. When the amount of beta detected changes the thickness must of changed. This source must half a long half life.

47
Q

What can ionising radiation cause

A

Tissue damage and cell mutation

48
Q

What do lower doses of radiation do

A

Minor damage without killing the cell leading to mutant cells which divide uncontrollably

49
Q

What effect do higher doses of radiation have

A

They tend to kill cells this causes radiation sickness

50
Q

How can you minimise exposure to radioactive isotopes in the lab

A

Never allow skin contact and handle with tongs, keep the source at arms length, keep it pointing away and don’t look at it. But the source in a lead box.

51
Q

What is a problem with nuclear fission reactor s

A

They create radioactive waste products, they can’t be recycled and usually have very long half lives.

52
Q

How do plants deal with radioactive waste

A

By vitrification , thy melt the waste with other materials to form a type of glass it is then sealed in steel canisters and buried . The general idea is to hide it in a place where the materials around it absorb the radioactive waste before it reaches the surface

53
Q

What are the negatives of nuclear power

A

Public perception is negative they see it as dangerous. Some believe nuclear waste can never be disposed of safely there is always a risk of leaks. Nuclear power carries the risk of major incidents such as Chernobyl . The building of the plant is extremely expensive and dismantling safely takes decades

54
Q

What are the pros of nuclear power

A

It is actually a pretty safe way of generating electricity . It is reliable and reduces the need for fossil fuels. It doesn’t real ease greenhouse gases like fossil fuels such as carbon dioxide . Huge amounts of energy can be generated from a relatively small amount of nuclear material . Fuel is pretty cheap and readily available

Physics P2 (2 decks)

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