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equations and key points triple science > Physics > Flashcards

Physics Flashcards

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1
Q

Difference of speed and velocity

Equation for average speed

A

Speed is just how fast you are going with no regard to direction.
Velocity is speed and direction.

Average speed = distance moved /time taken

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2
Q

Acceleration

A

Acceleration=change in velocity/time taken

Unit : m/s^2

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3
Q

Velocity time graphs.
What does a straight horizontal line show ?
Uphill line? Curve?

A

Shows how an objects velocity changes over time.
Flat horizontal lines means steady speed.
Uphill means acceleration and downhill means deceleration.
Curve is changing acceleration

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4
Q

Distance time graphs
What does a flat horizontal line represent ?
Steeper line?
Curve?

A

Flat line means it’s stopped
A steeper graph means it’s going faster
Curves represent acceleration

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5
Q

What is the force of attraction between all masses?
What is the difference between Mass and Weight?
What is weight measured in? Mass?
What is the equation linking mass weight and gravity?

A

Gravity.
Mass is the amount of stuff in an object, is it NOT a force.
Weight is caused by the pull of gravity. So it will be difference weight on the moon than on earth. Weight it a force measured in Newton’s.
Weight = mass x gravitational field strength
W= m x g

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6
Q

Name the different types of force.

What three ways does friction occur ?

A 
Gravity or weight.
Reaction force
Electrostatic force 
Thrust
Drag or air resistance 
Lift 
Tension

The three ways friction occurs is: friction between solid surfaces which are gripping
Friction between solid surfaces which are sliding past each other.
Resistance or drag from fluids and gases.

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7
Q

State the three laws of motion.

A

1st law : so long as the forces on an object are all balanced, then it will stay still, or else if it’d already moving it will just carry on at the same velocity- as long as all forces are balanced.

2nd law: if there is an unbalanced force, then the object will accelerate in that direction.

3rd law: if object a exerts a force on object b, object b will exert the equal and opposite force on object a.

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8
Q

The equation for resultant force.

A

Resultant force= Mass x acceleration

F=ma

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9
Q

What are vector quantities? What are scalar?

List four examples of both vector and scalar.

A

Vector quantities have force and direction.
Scalar only have size and No direction.
Vector; force, velocity, acceleration, momentum.
Scalar; mass, temperature, time, length.

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10
Q

Explain why an object falling through the sky will stop accelerating.

A

When an object starts falling it has much more acceleration than resistance slowing it down. As the velocity increases, the resistance builds up.
This resistance force gradually reduces the acceleration until eventually the resistance force is equal to the accelerating force, it has reached it maximum velocity or terminal velocity.

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11
Q

Explain Hooke’s law

A

The extension of a stretched wire is proportional to the load or force.

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12
Q

What is the equation for stopping distance?
What is thinking distance? What factors affect this?
What is braking distance? What factors affect this?

A

Stopping distance= thinking distance + braking distance.
Thinking distance is the distance the car travels in the time between the driver noticing the hazard and applying the breaks. This can be affected by how fast you are going and your reaction time (drugs, age, alcohol)

Braking distance is the distance the car travels during its deceleration whilst the brakes are being applied. This is affected by how fast you are going, the mass of the vehicle, how good your brakes are and how good the grip is.

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13
Q

Momentum equation

A

Momentum = mass x velocity

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14
Q

Forces cause changes in momentum equation

What designs in cars help slow down people over a period of time in a crash?

A

Force(N) = change in momentum/time
Crumple zones crumple on impact, increasing the time taken for the car to stop.
Seat belts stretch slightly,increasing the time taken for the wearer to stop. Reducing the forces on the chest.
Air bags also slow you down more gradually

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15
Q

Equation of moment

Where does the center of gravity hang?

A

Moment(Nm) = Force x perpendicular distance between line of action and pivot.
Below the point of suspension

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16
Q

What is current? Voltage? Resistance?

What is an ammeter ? The voltmeter ?

A

Current is the rate of flow of charge around a circuit.
Voltage is what drives the current round a circuit.
Resistance is anything that slows the flow down in the circuit.
Ammeter measures in amps, must be places in series but never parallel the component.
Voltmeter measures in volts, must be placed in parallel around the components under test

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17
Q

Formula linking V and I

A

Voltage= Current x Resistance

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18
Q

What is an LED? LDR?

A

Light-emitting diodes emit light when a current flows through them.
Light-dependent resistor changes it’s resistance depending how much light falls on it. In bright light the resistance falls and in darkness the resistance is highest.

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19
Q

Difference between series and parallel circuits?

A

Series is all or nothing while parallel has independent components.

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20
Q

What is the formula for charge?

A

Charge = current x time

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21
Q

Give the definition of the volt.

A

One volt is one joule per coulomb

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22
Q

Equation for energy transferred.

A

Energy transferred = charge X voltage.

23
Q

What color is the live, neutral, and earth wire?

A

Live wire is brown.
Neutral wire is blue.
Earth wire is green yellow.

24
Q

What are the volts of the live, neutral, earth wire?

A

The live wire alternates between a high ve and -ve of about 230v.
Neutral wire is always at 0v.
Earth wire is just for safety.

25
Q

How does a fuse work?

A

A fault in the live develops sending a surge thro the earth wire, this surge blows the fuse which cuts off live supply.

26
Q

Give the formula of electrical power

A

Electrical power = current X voltage.

27
Q

The equation involving frequency, wavelength and speed.

A

Speed = frequency x wavelength.

28
Q

What are transverse and longitudinal waves?

Give 3 examples of each.

A

Transverse waves, most waves. In transverse waves the vibrations are at 90 degrees to the direction energy is transferred by the wave.
Longitudinal wave vibrations are along the same direction as the wave transfers energy.
Transverse: light and all other EM waves. Waves on strings, ripples on water.

Longitudinal: sound and ultra sound. Shock waves, slinky when you push the end,

29
Q

What are wavefronts?

A

Wavefronts are imaginary planes that cut across all the waves connecting the points on adjacent waves which are vibrating together.

30
Q

What is the Doppler effect?

A

The Doppler effect makes waves appear longer or shorter.

31
Q

What are the seven types of EM waves? Name them in increasing frequency and decreasing wavelength.

A 
Radio waves
Microwaves
Infrared 
Visible light
Ultra violet 
X rays 
Gamma rays.
32
Q

Give the uses of radio waves, microwaves, infrared, and light signals .

A

Radio waves are used mainly for communications.

Microwaves are used for satellite communication and heating food.

Infrared radiation is used for heating and to monitor temperature.

Light signals can travel through optical fibers.

33
Q

Give the uses of visible light, ultra violet, x rays, and gamma radiation.

A

Visible light is useful for photography.

Ultraviolet is used in fluorescent lamps

X rays let us see inside things.

Gamma radiation can sterilizing medical equipment and sterilizing food.

34
Q

State the law of reflection

A

Angle of incidence = angle of reflection

35
Q

Define refractive index

A

Refractive index = speed of light in a vacuum/ speed of light in that material

36
Q

Smells law states…

A

N = sin i/ sin r

37
Q

What are sound waves?
What is the human ear capable of hearing?
How does the speed of sound change when in different densities?

A

Sound waves are longitudinal waves caused by vibrating objects.
The human ear is capable of hearing frequencies between 20 Hz and 20 000 Hz
Speed travels faster in solids that in liquids, and faster in liquids than in gases.

38
Q

Name the 8 energy stores.

A 
Kinetic
Thermal
Chemical
Gravitational potential
Elastic potential
Electrostatic
Magnetic
Nuclear
39
Q

Name the four main ways energy is transferred .

A

Mechanically
Electrically
By heating
By radiation

40
Q

What is the principle of conservation of energy?

A

Energy can be stored, transferred between stores and dissipated but it can never be created or destroyed. The total energy of a closed system has no net change

41
Q

When is energy useful

A

Energy is only useful when it is transferred from one store to a useful store.

42
Q

Equation for efficiency

A

Efficiency= useful energy output/ total energy output X 100

43
Q

Define thermal conduction

A

Thermal conduction is the process where vibrating particles transfer energy from their kinetic energy store to the Kinetic energy stores of neighboring particles.

44
Q

What is conduction and what is convection.

A

Conduction is the main form of energy transfer by heating in solids.

Convection is the main form of energy transfer by heating in liquids and gases.

45
Q

Define convection

A

Convection occurs when the more energetic particles move from the hotter region to the cooler region - and transfer energy as they do.

46
Q

Define ‘work done’.

A

When a force moves an object through a distance, WORK IS DONE on the object and ENERGY IS TRANSFERRED.

47
Q

Formula for work done

A

Work done = Force x Distance moved

48
Q

Formula for power

A

Power = work done / time taken

49
Q

Define power

A

Power is the rate at which energy is transferred

50
Q

Formula for energy in kinetic energy store

Formula for energy in G.p energy store

A

Energy in kinetic energy store = 1/2 x mass x (speed) ^2

GPE = mass x gravitational field strength x height

51
Q

What are the four non renewable sources

A

Coal
Oil
Natural gas
Nuclear fuels

52
Q

Formula for density
Pressure
And pressure difference

A

Density= mass/volume

Pressure = force/area

Pressure differences= height x density x gravitational field strength

53
Q

What is absolute zero , freezing point, and boiling point of water in Celsius and kelvin

A

Absolute zero is -273 C, freezing point is 0 C, and boiling point is 100 C
Absolute zero 0 K, freezing point is 273 K, and boiling point is 373 K

equations and key points triple science (3 decks)

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