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Physics The Good One > CPAC > Flashcards

CPAC Flashcards

1
Q

determine the acceleration of a freely falling object

A

set of two light gates to measure time and an electromagnet on a stand; measure the distance between the light gates; release the steel ball from the electromagnet; repeat for different distances between the light gates; using s = ut + 1/2at^2 plot 2s/t against t. The gradient is the acceleration

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2
Q

determine the acceleration of a freely falling object control variables

A

The distance from the point of release and the first light gate; the mass of the object / the object

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3
Q

Why use and electromagnet in ‘determine the acceleration of a freely falling object’

A

It means there is no force of propulsion so SUVAT can be used

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4
Q

risks in ‘determine the acceleration of a freely falling object’

A

falling objects, put padding on the falling region; tall unstable object, clamp to the table

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5
Q

Sources of uncertainty in ‘determine the acceleration of a freely falling object’

A

make sure the ruler is exactly vertical; normal resolution uncertainties

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6
Q

Determine the electrical resistivity of a material

A

Set up the wire in a circuit with an ammeter in series and a voltmeter in parallel; measure the diameter of the wire using a micrometer and calculate its area; measure the length of wire used in the circuit; measure the current and voltage; calculate the resistance of the wire; repeat for different lengths; plot a graph of R against 1/L

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7
Q

Determine the electrical resistivity of a material control variables

A

material of the wire; power supply

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8
Q

Determine the electrical resistivity of a material sources of uncertainty

A

measure diameter of wire (measure at 3 different points + check for zero error first); don’t leave power supply on as it heats up and affects the equation; regular resolution uncertainties

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9
Q

Determine the electrical resistivity of a material risks

A

electricity, check equipment is in good condition; cut wire, be aware of the sharp wire

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10
Q

Determine the emf and internal resistance of an electrical circuit

A

set up a variable resistor, ammeter and switch in series with a voltmeter in parallel over the supply; measure the pd and current for different resistances; plot V against I, the emf is the y intercept and the internal resistance is the gradient

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11
Q

emf =

A

V + Ir

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12
Q

Determine the emf and internal resistance of an electrical circuit hazards

A

electricity, check equipment is in good condition; heat/burning, disconnect wire between readings

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13
Q

Use a falling ball method to determine the viscosity of a liquid

A

measure the mass of the ball and the volume (measure how much water it displaced) then calculate the density; place two rubber bands on the tube which allows for a good time interval of the object moving at terminal velocity; drop the ball and measure the time it takes to get from the first band to the second; measure the distance between the rubber bands; calculate the density of the fluid; calculate viscosity using the gathered information

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14
Q

How do you measure the volume of an object

A

measure how much water it displaces

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15
Q

Use a falling ball method to determine the viscosity of a liquid control variables

A

drop the ball as close to the surface of liquid as possible

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16
Q

Viscosity =

A

(2r^2g(density of ball - density of fluid))/9v

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17
Q

Use a falling ball method to determine the viscosity of a liquid sources of uncertainty

A

may be errors in the human reaction time; uncertainty due to resolutions

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18
Q

Use a falling ball method to determine the viscosity of a liquid risks

A

split liquid, clean up spills immediately + keep tube away from the edge; elastic bands, wear safety goggles + don’t play with the bands

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19
Q

Determine the young modulus of a material

A

measure the diameter of the wire. Measure the original length of the wire. Attach the wire to the desk and thread it over a pulley with hanging masses on the end. Put a sticky label on the wire at the end of the metre ruler. Add the masses to the hanger and record the distance movement of the sticky marker. Plot extension against the weight (mg). The gradient is equal to length/area*young modulus.

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20
Q

Determine the young modulus of a material sources of uncertainty

A

measure the diameter 3 times and take an average; measure the masses individually and don’t just use the value given on the mass; regular resolution uncertainties

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21
Q

Determine the young modulus of a material sources of uncertainty risks

A

wire under strong force, wear safety goggles and make a paper bridge to go over the wire and absorb the energy from the wire; hanging masses, mark the area where it falls and avoid it

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22
Q

Young modulus =

A

stress / strain = Fl / Ae

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23
Q

Determine the speed of sound in air using a 2-beam oscilloscope, signal generator, speaker and microphone

A

Set up an oscilloscope with a signal generator and speaker a set distance from the microphone; turn the signal generator on. Adjust the oscilloscope to show 3 wave cycles; adjust the spacing between the microphone and the speaker until the waves line up. Then measure the distance between; move the speaker until the trace has moved exactly one cycle along and measure this distance; the difference between these distance is the wavelength; calculate the frequency by measuring the time period from the trace; calculate the velocity by using v = fλ

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24
Q

Determine the speed of sound in air using a 2-beam oscilloscope, signal generator, speaker and microphone sources of uncertainty

A

the image on the oscilloscope is likely to be unclear/ rapidly changing leading to a higher uncertainty; normal resolution uncertainties

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25
Q

Determine the speed of sound in air using a 2-beam oscilloscope, signal generator, speaker and microphone risks

A

high frequency sounds, only leave it one for when it is needed to avoid discomfort; electrical appliances, check its in a condition safe to use

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26
Q

Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire method 1

A

Attach a string to a vibration generator and thread it through a bridge and over a pulley with 100g of masses attached to the end; turn on the signal generator and vary the frequency until the string oscillates at its fundamental frequency. Record this frequency. Repeat this for 200g, 300g 400g and 500g; calculate the tensions in the string (T = W = mg); calculate how the wave speed changes with different tensions v= √(T/μ)

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27
Q

Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire method 2

A

Attach a string to a vibration generator and thread it through a bridge and over a pulley with 100g of masses attached to the end; turn on the signal generator and vary the frequency until the string oscillates at its fundamental frequency. Record this frequency, record the distance from the signal generator to the bridge; repeat for different lengths between the signal generator and bridge; plot a graph of λ against 1/f the gradient is the wave speed

28
Q

how to calculate mass per unit length

A

Take 1m of the string and weigh it

29
Q

Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire why different methods

A

Because its an investigation that finds relationships between a variable and the wave speed

30
Q

Determine the wavelength of light from a laser using a diffraction grating

A

place the laser a measured distance from the wall; place the diffraction grating between the wall and laser; mark the points of zero order and first order maxima. Measure the distance between n=0 and n=1; using the two distances calculate θ using trigonometry; using dλ = dsinθ work out λ

31
Q

Determine the wavelength of light from a laser using a diffraction grating sources of uncertainty

A

measure the distance from n=0 to n=1 either side then take an average; regular resolution uncertainties

32
Q

Investigate the effects of length, tension and mass per unit length on the frequency of a vibrating string or wire hazards

A

hanging masses, mark falling area and don’t stand there; wire under tension, wear goggles to protect eyes; electrical equipment, check apparatus is a suitable condition

33
Q

Investigate the relation between the force exerted on an object and its change of momentum

A

set up a trolley attached to masses by a string threaded over a pulley on a tilted ramp. Add a light gate near the bottom of the ramp; release the trolley from the top of the slope. Recording the distance to the light gate, the hanging masses, time taken to get to the light gate and the velocity at the light gate; repeat for different masses; plot mt against v. The gradient should equal g. Compare the calculated value to the actual value.

34
Q

momentum equation rearrange for question

A

Ft = mv - mu; mgt = mv

35
Q

Investigate the relation between the force exerted on an object and its change of momentum risks

A

hanging masses, keep feet away from falling area; moving trolley, make sure people are away when you’re about to complete the test

36
Q

Investigate the relation between the force exerted on an object and its change of momentum sources of uncertainty

A

human reaction time when timing will cause uncertainty; normal resolution uncertainties

37
Q

Investigate the relation between the force exerted on an object and its change of momentum control variables

A

angle of slope; distance between release and light gate; trolley mass/ wheel material; string elasticity

38
Q

Investigate the relation between the force exerted on an object and its change of momentum Why make the track a slope?

A

to counteract the effect of friction

39
Q

Use ICT to analyse collisions between small spheres method

A

measure the mass/diameter of spheres; start recording video and roll B into sphere A; repeat, varying the lines of approach so that the collision angles are different; using tracker software to calculate the momentum before and after the collision

40
Q

Use ICT to analyse collisions between small spheres risk

A

fast moving metal spheres could hit and hurt, so don’t propel them too fast; getting the camera correct in the setup, could fall and hurt so don’t set it up too high

41
Q

Use ICT to analyse collisions between small spheres sources of uncertainty

A

can’t easily repeat measurements as its hard to achieve the exact same velocity/angle; regular resolution percentage uncertainty

42
Q

Display and analyse the potential differential difference across a capacitor as it discharges through a resistor method

A

set up the circuit above with the first resistor; move the switch/flying lead to charge up the capacitor; record this pd and V0; move the switch for the capacitor to discharge and start the stopwatch; record the pd every 10 seconds; plot lnV against t. The gradient is -1/RC and the y intercept is lnV0

43
Q

Display and analyse the potential differential difference across a capacitor as it discharges through a resistor risk

A

capacitor retains charge which may cause shocks/electrocution so be sure to discharge; high voltage open circuit could cause shocks so don’t let the voltage exceed 40v

44
Q

capacitor discharge equation

A

V = V0e^-t/RC

45
Q

Display and analyse the potential differential difference across a capacitor as it discharges through a resistor sources of uncertainty

A

human error using a stopwatch; resolution uncertainties

46
Q

Display and analyse the potential differential difference across a capacitor as it discharges through a resistor controls

A

resistance of resistor; capacitance of the capacitor; same wire/ battery

47
Q

Calibrate a thermistor in a potential divider circuit as a thermostat

A

record the temperature of the water; put the thermistor in the beaker and record the resistance; repeat for a range of temperatures of water; plot resistance against temperature then for an unknown temperature record the resistance and read across to find the temperature

48
Q

What type of circuit is used to Display and analyse the potential differential difference across a capacitor as it discharges through a resistor

A

potential divider circuit

49
Q

Display and analyse the potential differential difference across a capacitor as it discharges through a resistor risks

A

water + electricity could result in an electric shock; hot water could scald; glass beaker if broken could cut

50
Q

Display and analyse the potential differential difference across a capacitor as it discharges through a resistor control variables

A

same resistor; same beaker so same surface area of liquid

51
Q

Determine the specific latent heat of ice method

A

measure 50g of ice into the funnel and wait until it reaches 0 degrees; record the mass of an empty dry beaker; put 100cm^3 of water in the empty beaker and record the total mass m, and the temperature of water; add the 0 degrees ice to the water beaker; record the lowest temperature reached by the ice/water mixture; determine the final total mass of the ice water and beaker; Energy received by ice = Energy released by water; Lm (of ice) + mc(t1-t2)

52
Q

Determine the specific latent heat of ice control variables

A

mass of water, heat of the water, mixing surface area

53
Q

Determine the specific latent heat of ice risks

A

spills of water or ice, clean up immediately

54
Q

Determine the specific latent heat of ice sources of uncertainty

A

unobserved heat loss from the system; errors due to difficulty measuring temperature accurately due to fluctuations; errors in recording mass of water

55
Q

q

A

a

56
Q

Investigate the relationship between the pressure and volume of a gas at fixed temperature method

A

either use Boyles law equipment or…\nusing a syringe, fix a set mass of gas by sealing off the end. Measure the diameter of the syringe in three places, then calculate the area. Hang masses to change the force, measure the length the syringe increased by each time to get the volume. Calculate the pressure. Plot pressure against 1/volume; if it’s directly proportional, it obeys Boyle’s law.

57
Q

Investigate the relationship between the pressure and volume of a gas at fixed temperature risk

A

High pressure, so a safety screen may be necessary + wear goggles.

58
Q

Investigate the relationship between the pressure and volume of a gas at fixed temperature sources of uncertainty

A

Atmospheric pressure may affect the graph, meaning it won’t go through (0,0). Resolution uncertainties.

59
Q

Investigate the relationship between the pressure and volume of a gas at fixed temperature control variables

A

Speed of pumping may cause heating if done too fast.

60
Q

Investigate the absorption of gamma rays by lead method

A

Measure the width of varying lead sheets using the micrometer. Record the background radiation by measuring the counts in 1 minute. With each sheet of lead, record the counts per minute and subtract the background radiation from it. Plot width against ln counts; the gradient is the decay constant and the y-intercept is ln C.

61
Q

Investigate the absorption of gamma rays by lead risks

A

Radioactive material can be bad for health, so point the source away and do not touch. Lead can be poisonous if it enters the bloodstream.

62
Q

Investigate the absorption of gamma rays by lead sources of uncertainty

A

The further away from the source, the less intense the radiation. Resolution uncertainties.

63
Q

Investigate the absorption of gamma rays by lead control variables

A

Distance of the source from the lead. Source of radiation (and intensity).

64
Q

Determine the value of an unknown mass using the resonant frequencies of known masses on a spring method

A

Record the time for 10 oscillations. Change the mass and repeat. Find the time for one oscillation, then square it. Draw a graph of T^2 against mass. Find the time for an unknown mass, then use the graph to determine the mass.

65
Q

Determine the value of an unknown mass using the resonant frequencies of known masses on a spring risks

A

Spring could pin and hit the eye, so wear goggles. Masses hanging from a stand could fall, so clamp to the table.

66
Q

Determine the value of an unknown mass using the resonant frequencies of known masses on a spring control variables

A

Human error, so record time for 10 oscillations to reduce. Measure masses individually with a top pan balance. Resolution uncertainties.

67
Q

Determine the value of an unknown mass using the resonant frequencies of known masses on a spring sources of uncertainty

A

Same spring (so same stiffness).

Physics The Good One (16 decks)

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