A2 Physics Practical

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Student 1 of 2

Practical 1 Momentum and momentum conservation largetrolleys

Figure 1: Arrangement of large trolleys to investigate momentum and momentum conservation

Experimental instructionsSet up the apparatus as shown in the diagram with fve slotted masses fxed onto trolley A.Compensate or riction by tilting the runway slightly. Check by giving one trolley a small

push and confrming that it runs down the runway with constant speed.

So ten the Plasticene and stick it to the ront o one o the trolleys. Fix the drawing pin tothe ront o the other trolley with the adhesive tape, so it is acing out rom the trolley asshown. Put the two light gates quite close together. This is to minimise the e ects o rictionas the trolleys collide.

Set the inter ace unit to record the speed o trolley A be ore the collision and the speed o thetwo trolleys (A and B joined together) a ter the collision.

Put trolley A at one end o the runway and trolley B just be ore light gate 2.

Give trolley A a push (not too large) so that it runs down the track, cutting through the lightbeam o light gate 1 and colliding with, and sticking to, trolley B. The two trolleys will nowtravel on, the mask on trolley A cutting through the light beam o light gate 2.

light gate 1 light gate 2

trolley A trolley B

Plasticene

Plasticene Drawing pin Adhesive tape Means of tilting the runway

You will need: Two trolleys Two light gates and suitable interface Eight 100 g slotted masses Wooden runway

The aim of this experiment is to study momentumand its conservation in an inelastic collision.

Purpose

Lift the large wooden runway with care.Set up the experiment away from the edges of the bench so that the trolleys do not fall off.

Safety


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Student 2 of 2

Practical 3 (cont.) Momentum and momentum conservation using alinear air track

Analysis and conclusionsCalculate the total momentum o both riders be ore and a ter the collision. Use your resultsto test the law o conservation o momentum.

Comment on the most important sources o error in your experiment and how they mightbe reduced.


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Student 2 of 2

Practical 4 (cont.) Rate of change of momentum using a linear air track

Vary the accelerating force but keep the total mass constant by putting masses on the riderif they are removed from the hanger and vice versa. Record the values of acceleratingforce, velocity and momentum values at gates 1 and 2, the momentum change and the timebetween the light gates in a table.

Analysis and conclusionsCalculate the rate of change of momentum for each accelerating force.

Plot a graph of rate of change of momentum against accelerating force.

Comment on the shape of graph and deduce the relationship between rate of change of

momentum and accelerating force.


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1 of 2 Student

Practical 5 Rate of change of momentum using a trolley

Figure 1: Using a trolley to investigate rate of change of momentum

Experimental instructionsSet up your apparatus as shown in the diagram. Compensate the runway for friction byraising one end slightly. Check by giving the trolley a gentle push and measuring its velocitythrough both light gates it should move along the runway at a constant velocity when thereis no accelerating force on it. Set your interface unit to measure velocity at both gates and thetime taken to travel between them.

Start with ten of your twelve washers on the trolley and the other two on the thread hangingdown. The mass to be accelerated is the mass of the trolley and twelve washers while theaccelerating force is the weight of the two suspended washers (0.2 N).

Allow the trolley to accelerate down the runway. Record the velocities of the trolley as it

passes through light gates 1 and 2 and the time take for the trolley to travel between thegates. Repeat the readings and take an average.

washers

accelerating washers

trolley

mask size 1 cm

light gates

Thread Twelve washers (mass 10g each) (a set of

slotted masses could be used instead of thewashers)

Sponge to put on oor below the masses

You will need: Trolley White plastic track

Board Two light gates and suitable interface Bench pulley

Purpose

The aim of this experiment is to investigate rate of change of momentum using a trolley on arunway.


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Student 2 of 2

Practical 5 (cont.) Rate of change of momentum using a trolley

Repeat the procedure by taking one washer off the trolley and adding it to the suspendedwashers the accelerating force is now 0.3 N (same total mass). Carry on until you haveonly two washers left on the trolley. Record the values of accelerating force, velocity andmomentum values at gates 1 and 2, the momentum change and the time between the lightgates in a table.

Analysis and conclusionsCalculate the rate of change of momentum for each accelerating force.

Plot a graph of rate of change of momentum against accelerating force.

Comment on the shape of graph and deduce the relationship between rate of change of momentum and accelerating force.


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1 of 1 Student

Practical 6 Centripetal force whirling bung

Experimental instructionsTie the piece of string to a rubber bung and then threadit through a short length (10 cm) of glass tube. Fix a smallweight (such as a few washers with a mass a little greater thanthe mass of the bung) to the lower end of the string.

Whirl the bung round in a horizontal circle (radiusapproximately 80 cm) while holding the glass tube so thatthe radius of the bungs orbit is constant. (A mark on thestring will help you see if the radius of the orbit remains thesame.)

Measure the mass of the bung ( M ), the total mass of thewashers ( m), the radius of the orbit ( R ) and the time for tenorbits (10 3 T ).

Stopwatch or stop clock Metre ruler Short length of glass tube with the ends

burred over (or a short metal tube)

Access to a balance Eye protection

You will need:

Rubber bung with a hole through it Length of string (about 1.5 m) Washers or 10 g slotted masses and

hanger

Purpose

The aim of this experiment is to verify theequation for centripetal force using a whirlingbung.

Do not swing the bungs round too fast and avoidcollisions between bungs and people!Keep away from windows.Wear eye protection.

Safety

R

rubber bungmass M

washers or slotted masses

(weight mg )

glass tube

Figure 1: Whirling bung arrangement

Repeat the experiment with different numbers of washers, different orbit radii and bungs of different masses.

Analysis and conclusionsCalculate the period of the orbit ( T ), the velocity of the bung in the orbit ( v 5 2 p R ____ T )andthen work out the centripetal force ( F 5 Mv 2 ____ R ) .Compare this value with the weight of the washers ( mg ).

(The centripetal force should be equal to the weight of the washers. This will only be the caseif the system is frictionless.)

Plot a graph of m against v2.


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Student 1 of 1

Practical 7 Centripetal force rotating trolley

Figure 1: Rotating trolley setup

Experimental instructionsSet up the apparatus as shown, clamping the rotating table frmly to the bench. Care ully increasethe speed o the motor until the trolley just touches the stop at the end o the runway. Measurethe rotation rate and use it to calculate the speed ( v ) o the trolley in a circle o radius R .

Measure the mass o the trolley and its load ( m ) and hence calculate the theoretical value o the centripetal orce needed to keep it in the orbit at that speed ( centripetal orce 5 mv 2 ____ R ) .Using a newtonmeter, measure the orce required to extend the spring by the amount neededor the trolley to touch the end o the runway. Compare your two values and comment onyour fndings.

Repeat the experiment or di erent values o the load on the trolley.

Analysis and conclusionsPlot a graph o the measured orce against mv 2. Use the graph to veri y the equation orcentripetal orce.

Power supply (012V) Ruler Stop clock Newtonmeter Balance G clamps

You will need: Trolley Spring Plastic runway Wooden support Washers Rotating table

Do not allow the rotating table to turn too fast!

SafetyPurpose

The aim of this experiment is to verify theequation for centripetal force.

spring

rotating table

washers

trolley

runway

R


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1 of 1 Student

Practical 8 Measuring the charge stored by a capacitor

Figure 1: Circuit for measuring the charge stored by a capacitor

Experimental instructionsConnect up the circuit shown in the diagram using the 0.1 m F capacitor, with the switch inposition 1. Switch on the power supply and adjust the output so that the voltmeter reads 0.5 V.

Move the switch to position 2 and record the reading of charge on the coulombmeter.

Return the switch to position 1, and adjust the voltmeter to read 1.0 V. Move the switch toposition 2 and again record the charge.

Repeat the procedure in 0.5 V steps up to a maximum of 6.0 V. Record all your results in atable showing capacitor voltage and charge.

Repeat for different values of capacitance.

Analysis and conclusions

Circuit using batterypack and rheostatC

Circuit using variablevoltage power supply

d c p o w e r s u p p

l y

( 0

6 V

)

21

C

21

V Q

V Q

Power supply (06V dc) (or6 V battery pack and a 10 V

rheostat)

Digital coulombmeter Digital voltmeter SPDT switch

You will need: Capacitors (0.1m F, 0.22m F,

0.047 m F)

The aim of this experiment is to measure the charge stored by acapacitor using a coulombmeter and to investigate the formula

capacitance 5charge ________

potential ( C 5 Q __ V ) .

Purpose

If you are using an electrolyticcapacitor, take care to connectit with the correct polarity.

Safety


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Practical 9 Effect of length and current on the force on a wire in amagnetic field

Figure 1: The experimental arrangement

Experimental instructionsSet up the apparatus as shown with the crocodile clips a measured distance apart (say 4 cm).Take the reading on the balance and then switch on the power supply so that a current o 5 Afows through the rod. I necessary, change the direction o the current fow so that it causesan increase in the balance reading. Record the new reading o the balance.

Change the separation o the crocodile clips and repeat the reading, keeping the currentconstant. Note that the separation o the crocodile clips must not be greater than the lengtho the magnet poles. Repeat or a number o di erent crocodile clip separations.

Two crocodile clips Ammeter (05A dc) 30cm ruler Two retort stands Bosses and clamps

You will need: Electronic balance Length of thin copper rod Power supply (012V dc, 05A) 4 mm connecting leads Strong U-shaped magnet (two magnadur

magnets on a yoke can be used if thebalance is suf ciently sensitive)

Purpose

The aim of this experiment is to investigate how the force experienced by a current-carrying wirein a magnetic eld depends on the length of the wire and the current passing through it.

front view

to power supply

magnets fixedto metal yoke

copper rod

side view

245

Student 1 of 2


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Practical 9 (cont.) Effect of length and current on the force on a wirein a magnetic field

Analysis and conclusionsCalculate the orce on the current using the equation F 5 BIl (i B is known) and compare itwith the increase in the balance reading.

I the value o B is not known, use the increase in balance reading ( 5 mg ) to calculate it.

Plot graphs o orce against crocodile clip separation and orce against current. Comment onyour graphs.

2 of 2 Student


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Student 1 of 2

Practical 10 Specific heat capacity of a liquid

Experimental instructionsSet up the apparatus as shown in the diagram. Measure the mass o the calorimeter ( m C ) andfll it with a known mass o water ( m W ). There must be enough water to cover the immersionheater when it is put in the calorimeter. Place the mu over the calorimeter.

Switch on the heater. Set the voltage ( V ) to a convenient value and record this with the valueo the current ( I ). Measure the initial water temperature ( u ) using a thermometer and startthe stop clock (or use a temperature sensor and data logger). Record the temperature at one-minute intervals, stirring just be ore the thermometer is read. Switch o the heater when thetemperature reaches 50 C.

Do not heat the contents of the calorimeter

above 50 C.

Safety

The aim of this experiment is to measure thespeci c heat capacity of a liquid using an electricalmethod.

Purpose

Low-voltage power supply (012V) Thermometer (050C) Stop clock (A temperature sensor and data logger canbe used instead of the thermometer and stopclock.)

You will need: A copper or aluminium calorimeter with a

volume of between 250 and 400 ml Insulating jacket with a hole for the

thermometer or sensor Electrical immersion heater Voltmeter Ammeter

insulating muff

Stirrer

water

heater

Figure 1: Calorimeter setup or measuring the specifc heat capacity o a liquid


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2 of 2 Student

Practical 10 (cont.) Specific heat capacity of a liquid

Analysis and conclusionsPlot a graph o temperature against time and choose a section o the graph where thetemperature is rising steadily. In this area fnd the temperature rise u in a time t .

Calculate the electrical energy supplied to the heater ( VI t ).

Assume that there are no heat losses during the experiment.

Calculate the specifc heat capacity o water ( c W ) rom the equation:

VI t 5 m C c C u 1 m W c W u

where c C

is the specifc heat capacity o the material o the calorimeter. (The value o c C

canbe ound rom a data book.)

Repeat the experiment with other liquids.

Record any sources o error which you consider will a ect your result.

Predict the e ect on your answer o signifcant heat loss.


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Student 1 of 2

Practical 11 Specific heat capacity of a solid

Figure 1: Setup or measuring the specifc heat capacity o a solid

Experimental instructionsMeasure the mass o the metal block ( m ). Put the thermometer in the small hole in the metalblock. Place the heater in the large hole in the block and switch it on. A small amount o silicone grease in the holes in the block can improve thermal contact. Place the insulatingjacket around the apparatus.

Stop clock Insulating jacket with a hole for the

thermometer or sensor Silicone grease(A temperature sensor and data logger canbe used instead of the thermometer and stopclock.)

You will need: Aluminium (or other metal block) with a

mass of 1 kg

Heat-resistant mat Low-voltage heater and suitable power

supply Ammeter and voltmeter Thermometer (050C)

Purpose

The aim of this experiment is to measure the speci c heat capacity of a solid using an electricalmethod.

metal block

immersion heater

insulating jacket

heat-resistant mat


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Practical 12 The relationship between the pressure andtemperature of a gas

Experimental instructionsSet up the apparatus as shown in the diagram with some icein the water to cool it to near 0 C.

Record the temperature o the water (e ectively the

temperature o the air in the fask) and the pressure o the airas shown on the Bourdon gauge.

Light the Bunsen burner and heat the water slowly. Recordthe pressure and temperature o the air at 10-degree intervalsuntil the water temperature reaches 80 C. (The temperaturesensor may record temperatures at equal time intervals.)

Analysis and conclusionsPlot a graph o the pressure o the trapped air ( y -axis)

against the temperature o the trapped air ( x -axis). (Makesure that the pressure you record is the pressure o thetrapped air, not just the excess above atmospheric pressure).It is assumed that the temperature o the trapped air will bethe same as that o the water in the beaker.

Wear eye protection if your face is to be close tothe hot water.

Safety

The aim of this experiment is to investigate howthe pressure of a gas changes when it is heated ata constant volume.

Purpose

water

heat

Bourdongauge

air

Length of rubber tubing

Pressure sensor (or Bourdon gauge) Bunsen burner, tripod, gauze and mat Glass beaker

Water

Ice Eye protection

You will need: Round-bottomed ask

Temperature sensor and probe(or 0100 C thermometer)

Rubber bung with a short length of glasstube tted through it

Figure 1: Investigating the relationship betweentemperature and pressure

Draw a second graph with the temperature axis showing minus 300 C to plus 100 C andnd the intercept on the pressure axis (when the gas has zero pressure). This should be atabsolute zero.

Record your value or absolute zero, suggesting any inaccuracies in your experiment andhow they might be reduced.

Student 1 of 1


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1 of 1 Student

Practical 13 The relationship between the pressure and volume of a gas

Experimental instructionsUse the special apparatus shown in the diagram.

Using the bicycle pump, pump up the oil until the volumeo trapped air is less than hal the original value as shown onthe vertical scale.

Record the pressure ( p ) and volume ( V ). The tubecontaining the air can be taken as having a uni orm bore, sothe length o the trapped air column is proportional to itsvolume.

Slowly reduce the pressure by opening the valve at the baseo the apparatus a ter disconnecting the pump. Close thevalve a ter the oil level has allen a little, wait or any excessoil to drain down the sides, and then take another reading o

p and V .

Repeat the procedure to gain as many readings as possibleas the pressure o the trapped air, and there ore the oil level,alls.

Take readings o the air temperature next to the apparatusto make sure that it does not alter signifcantly during theexperiment.

The aim of this experiment is to verify therelationship between the pressure ( p) and volume(V ) for a gas.

Purpose

The apparatus should include a protectiveplastic screen around the glass tube.However, a safety screen is advisable.Do not increase the pressure to more than300 kPa.

Safety

kPa

trapped air

to pump

oil

Figure 1: Boyles law apparatus

Analysis and conclusionsPlot two graphs:

a one o p against V and b one o p against 1 __ V

.

Length of thick-walled rubbertubing

Thermometer Safety screen

You will need: Boyles law apparatus Bicycle pump


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2 of 2 Student

Practical 14 (cont.) Measurement of the activity of a radioactivesource

Analysis and conclusionsCalculate the sur ace area o the sphere radius R (4 p R 2) and the area o the GM tubewindow ( p r 2).

Calculate the activity o the source using the equation:

activity o the source 5 count rate 3 4p R 2 _____ p r 2

You will have to ignore the absorption o the intervening air and the GM tube end window.


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Practical 16 Graphical representation of simple harmonic motion

Experimental instructionsSet up the apparatus shown in the diagramwith the motion sensor positioned below theslotted masses and in line with the direction of oscillation. The exact arrangement will dependon the design of your motion sensor.

Five experiments should be performed to enableyou to plot graphs of:

a acceleration against distance from the centreof oscillation

b velocity against distance from the centre of oscillation

c distance against time

d velocity against time

e acceleration against time.

Use the data logger to display and record thegraphs.

Set of slotted masses and hanger (100 g each) 30cm ruler

Retort stand, boss and clamp

You will need: Helical spring Motion sensor

Suitable data logger

Purpose

The aim of this experiment is to generate graphs of some of the different properties of a systemundergoing simple harmonic motion. This can be done using a motion sensor and data logger.

helical spring

slotted masses

motion sensor

Figure 1: The experimental arrangement

1 of 1 Student


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A2 Physics Practical

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