191234098 Pressure Questions for IGCSE Physics

8/18/2019 191234098 Pressure Questions for IGCSE Physics

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1 The diagram shows a simple mercury

barometer.

If atmospheric pressure increases, what happensto level X and to level Y?

2 A measured mass of gas is placed in a cylinderat atmospheric pressure and is then slowlycompressed.

If the temperature of the gas does not change,what happens to the pressure of the gas?A It drops to zero.B It decreases, but not to zero.C It stays the same.D It increases.

3 The diagram shows an instrument used to

measure gas pressure.

What is the instrument called?A ammeter

B barometerC manometerD thermometer

4 The diagrams show two divers swimming in thesea and two divers swimming in fresh water. Seawater is more dense than fresh water.

On which diver is there the greatest pressure?

5 The air trapped in a cylinder by a piston is kept

under pressure by a load, as shown inFig. 4.1.

(a) Describe how the pressure in the cylinder iscaused by the air molecules.(b) The load is increased.(i) State what happens to the piston.(ii) State what happens to the pressure in the

cylinder, and give a reason.what happens

6 Which diagram shows the child exerting least

pressure on the ground?

7 A manometer is being used to measure thepressure of the gas inside a tank. A, B, C and Dshow the manometer at different times.At which time is the gas pressure inside the tank

greatest?


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8 Driving a car raises the temperature of the tyres.This causes the pressure of the air in the tyres toincrease.Why is this?A Air molecules break up to form separate atoms.B Air molecules expand with the rise intemperature.C The force between the air molecules increases.D The speed of the air molecules increases

9 (a) A farmer has two vehicles with the sameweight and the same number of wheels.Fig. 4.1 shows what the wheels on these two

vehicles look like.

Which vehicle should the farmer use when drivingacross his fields when the ground isvery soft? Give your reasons.(b) (i) If you stepped on the point of a sharp nail

with your bare foot, it would beextremely painful. Explain, in terms of pressure,why this is so.(ii) A person can lie on a bed of nail-points if

there is a large number of nails. Explainwhy this is not extremely painful.

10 Fig. 2.1 shows a diver 50 m below the surface

of the water.

(a) The density of water is 1000 kg/m3 and theacceleration of free fall is 10 m/s2.Calculate the pressure that the water exerts onthe diver.(b) The window in the diver’s helmet is 150 mm

wide and 70 mm from top to bottom.Calculate the force that the water exerts on thiswindow.


barometer. The barometer reading is hcm of

mercury

What is the pressure at S? A approximately zeroB atmospheric pressureC atmospheric pressure + hcm of mercuryD hcm of mercury

12 Two boys X and Y each have the same total

weight and are standing on soft ground.

Which boy is more likely to sink into the soft

ground and why?

13 A student places his thumb firmly on the outlet

of a bicycle pump, to stop the air coming out.


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What happens to the pressure and to the volumeof the trapped air as the pump handle is pushedin?

14 A balloon is inflated in a cold room. When theroom becomes much warmer, the balloonbecomeslarger.How does the behaviour of the air molecules inthe balloon explain this? A The molecules become larger.B The molecules evaporate.C The molecules move more quickly.

D The molecules repel each other.

15 Liquid X has a density of 1010 kg / m3. LiquidY has a density of 950 kg / m3.The liquids are poured into tubes as shown.Which tube has the greatest pressure on its base?

16 The diagram represents gas moleculescontained in a cylinder. The piston is movedslowlydownwards and the temperature of the gas stays

the same.

Why does the pressure of the gas increase? A The molecules collide harder with the walls.B The molecules collide more often with the walls.C The molecules move more quickly.D The number of molecules increases.

17 (a) In Fig. 2.1, the sealed drum containing gashas a mercury manometer connected to it inorder to indicate the gas pressure.

For convenience, gas pressure is often expressedin mm of mercury.The gas pressure is 781 mm of mercury and airpressure is 760 mm of mercury.(i) State the difference in height between levels Aand B on the manometer.difference in height = ………….………..mm

(ii) The temperature of the gas rises.State what happens to1. the gas pressure,2. the level A,3. the level B.(b) The air in part (a) is also pressing on a largewindow pane in the wall of the room wherethe drum is situated.(i) State how the air pressure on the window panecompares with the air pressure onthe mercury surface at B in Fig. 2.1.(ii) State how the force exerted by the air on the

window pane compares with the forceexerted by the air on the mercury surface at B.

18 Fig. 2.1 shows a reservoir that stores water.

(a) The valve in the exit pipe is closed. Thedensity of water is 1000 kg/m3 and theacceleration of free fall is 10 m/s2.

Calculate the pressure of the water acting on theclosed valve in the exit pipe.(b) The cross-sectional area of the pipe is 0.5m2.

Calculate the force exerted by the water on theclosed valve.(c) The valve is then opened and water, originally

at the surface of the reservoir, finally


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flows out of the exit pipe. State the energytransformation of this water between thesurface of the reservoir and the open end of thepipe.

19 A water manometer is used to measure thepressure of a gas supply to a house. It gives areading of h cm of water.

Why is it better to use water rather than mercuryin this manometer? A h would be too large if mercury were used.

B h would be too small if mercury were used.C The tube would need to be narrower if mercurywere used.D The tube would need to be wider if mercurywere used.

20 A farmer has two carts. The carts have thesame weight, but one has four narrow wheels andthe other has four wide wheels.

In rainy weather, which cart sinks less into softground, and why?

21 A measured mass of gas is placed in a cylinderat atmospheric pressure and is then slowlycompressed.

The temperature of the gas does not change.What happens to the pressure of the gas? A It drops to zero.B It decreases, but not to zero.C It stays the same.D It increases.

22 An experiment is set up as shown.

What does the pressure gauge show as the air inthe flask becomes hotter? A a steady pressureB a decrease in pressureC an increase in pressureD an increase and then a decrease in pressure

23 (a) On a hot day, a child drinks all the water ina plastic bottle. She then screws the capback tightly on the bottle, so that the bottlecontains only air.

She throws the bottle into a waste basket, wherethe Sun shines on it. After a while in the Sun’s rays, the air in the bottleis much hotter than before.(i) State what has happened to the pressure of theair in the bottle.

(ii) In terms of the behaviour of the air molecules,explain your answer to (a)(i).

(b) Also in the waste basket is a broken glassbottle containing a small quantity of water, asshown in Fig. 5.2.

As the Sun shines on it, the volume of waterslowly decreases.(i) State the name of the process causing thisdecrease.


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(ii) In terms of the effect of the Sun’s rays on thewater molecules, explain your answerto (b)(i).

24 The diagram shows a mercury barometer.

Which distance is used to calculate the pressureof the atmosphere? A 25 cm B 75 cm C 80 cm D 100 cm

11 Four blocks, each weighing 10 N, rest on ahorizontal table.

Which block applies the greatest pressure on thetable?

25 (a) Fig. 3.1 shows two examples of footwearbeing worn by people of equal weight at aWinter Olympics competition.

Which footwear creates the greatest pressurebelow it, and why?(b) Drivers of high-sided vehicles, like the one in

Fig. 3.2, are sometimes warned not todrive when it is very windy.

Suggest why they receive this warning.

26 Fig. 3.1 shows a pond that is kept at a constantdepth by a pressure-operated valve in thebase.

27 Fig. 3.1 shows a pond that is kept at a constantdepth by a pressure-operated valve in thebase.

(a) The pond is kept at a depth of 2.0 m. Thedensity of water is 1000 kg/m3.Calculate the water pressure on the valve.(b) The force required to open the valve is 50 N.

The valve will open when the water depth

reaches 2.0 m.Calculate the area of the valve.(c) The water supply is turned off and the valve is

held open so that water drains outthrough the valve.State the energy changes of the water that occuras the depth of the water drops from2.0 m to zero.

28 Fig. 5.1 shows a way of indicating the positionsand direction of movement of somemolecules in a gas at one instant.

(a) (i) Describe the movement of the molecules.

(ii) Explain how the molecules exert a pressureon the container walls.(b) When the gas in the cylinder is heated, it

pushes the piston further out of the cylinder.State what happens to(i) the average spacing of the molecules,(ii) the average speed of the molecules.(c) The gas shown in Fig. 5.1 is changed into a

liquid and then into a solid by cooling.Compare the gaseous and solid states in terms of(i) the movement of the molecules,(ii) the average separation of the molecules.

29 (a) For a special parade, the guest of honour isto sit on a chair whilst the parade passesby. Unfortunately the ground beneath the chair issoft, so the parade organisers put thechair on a large flat board, as shown in Fig. 1.1.


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Explain why the board prevents the chair fromsinking into the ground.(b) At the parade, some air-filled balloons areused as decorations, as shown in Fig. 1.2.

(i) State what happens to the balloons when theSun makes them hotter.(ii) In terms of molecules, explain your answer to

(b)(i).

(c) A pump is used to pump up the balloons in (b). A valve in the pump becomes blocked,as shown in Fig. 1.3.

(i) The piston of the pump is pushed in. Statewhat happens to the pressure of the airtrapped in the pump.(ii) In terms of molecules, explain your answer to

(c)(i).

30 To prevent a cement mixer sinking into softground, the mixer is placed on a large flat board.

Why does this prevent the mixer sinking? A The large area decreases the pressure on theground.B The large area increases the pressure on theground.C The large area decreases the weight on theground.D The large area increases the weight on theground.


barometer.

The atmospheric pressure increases.Which distance increases? A VW B WY C XY D XZ

32 A pressure is measured using a manometer asshown in the diagram.

The water in the manometer is replaced with aliquid which is more dense.How does the value of h change? A It becomes zero.

B It decreases, but not to zero.C It stays the same.D It increases.

32 A cylinder is filled with a gas and then sealed,so that the gas has a fixed volume.


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The gas molecules are given energy so that theiraverage speed increases.What happens to the pressure and to thetemperature of the gas in the cylinder?

33 (a) Fig. 6.1 shows how the pressure of the gassealed in a container varies during a periodof time.

Which of the following statements could explainthis variation of pressure?Tick two statements.

(b) Fig. 6.2 shows some gas trapped in a cylinderwith a movable piston.

The temperature of the gas is raised.(i) State what must happen to the piston, if

anything, in order to keep the pressure ofthe gas constant.(ii) State your reasons for your answer to (b)(i).

34 Fig. 2.1 shows a steam safety valve. When thepressure gets too high, the steam lifts theweight W and allows steam to escape.

(a) Explain, in terms of moments of forces, howthe valve works.(b) The moment of weight W about the pivot is 12

N m. The perpendicular distance of theline of action of the force of the steam on the

valve from the pivot is 0.2 m.The area of the piston is 0.0003 m2.Calculate(i) the minimum steam force needed for the steamto escape,(ii) the minimum steam pressure for the steam to

escape.

35 The diagram shows a simple mercurybarometer, used to measure atmosphericpressure.

Atmospheric pressure increases.What happens to the level L and to the pressureat P?

36 The gas in a container is heated but is kept atconstant volume.Why does the gas pressure increase? A The molecules expand.B The molecules increase in mass.C The molecules move further apart.


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D The molecules move more rapidly.37 Fig. 3.1 shows a simple mercury barometer,drawn 1/10 full size.

(a) On Fig. 3.1, use your rule to make anappropriate measurement, and then use it tocalculate the atmospheric pressure.(b) State what occupies the space in the tube

above the mercury.

12 A manometer is used to indicate the pressurein a steel vessel, as shown in the diagram.

What value does the liquid manometer give for thepressure in the vessel? A It is zero.B It is between zero and atmospheric pressure.

C It is equal to atmospheric pressure.D It is greater than atmospheric pressure.

38 Four glass tanks contain water.In which tank is the pressure of the water on thebase greatest?

39 The diagram shows a simple mercurybarometer used to measure atmosphericpressure.

Which statement is correct? A The pressure at P is atmospheric pressure.B The pressure at P is nearly zero.C The pressure at Q is lower than the pressure atP.D The pressure at Q is nearly zero.

40 A brick with rectangular sides rests on a table.

The brick is now turned so that it rests on thetable on its smallest face.

How has this change affected the force and thepressure exerted by the brick on the table?

41 The pressure of a fixed mass of gas in acylinder is measured. The volume of the gas inthecylinder is then slowly decreased.Which graph could show the change of pressureof the gas during this process?


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42 Fig. 6.1 shows two mercury barometersstanding side by side. The right-hand diagram isincomplete. The space labelled X is a vacuum.

(a) On the left-hand barometer, carefully mark thedistance that would have to be measuredin order to find the value of the atmosphericpressure. [2](b) A small quantity of air is introduced into X.(i) State what happens to the mercury level in thetube.(ii) In terms of the behaviour of the air molecules,

explain your answer to (b)(i).(c) The space above the mercury in the right-

hand barometer is a vacuum.On Fig. 6.1, mark the level of the mercury surface

in the tube.(d) The left-hand tube now has air above the

mercury; the right-hand tube has a vacuum.Complete the table below, using words chosenfrom the following list, to indicate theeffect of changing the external conditions.rises falls stays the same

43 The diagrams show two mercury barometersstanding side by side. The right-hand diagramshows a tube of bigger diameter, but the diagramis incomplete. There is a vacuum above the

mercury in both tubes.Which labelled position on the right-hand tubecould show the mercury level in that tube?

44 A student fills two containers with water(density 1.0 g / cm3) and two with oil (density 0.8 g/ cm3),as shown in the diagrams.In which container is the pressure on the base thegreatest?

45 A piston traps a certain mass of gas inside acylinder. Initially the piston is halfway along thelength of the cylinder.

The piston is now moved towards the open end ofthe cylinder. The temperature of the gasremains constant.

How are the density and the pressure of the gasaffected by moving the piston?

46 Fig. 4.1 shows a manometer, containingmercury, being used to monitor the pressure of agas supply.


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(a) Using the scale on Fig. 4.1, find the verticaldifference between the two mercury levels.(b) What is the value of the excess pressure ofthe gas supply, measured in millimetres ofmercury?(c) The atmospheric pressure is 750 mm of

mercury.Calculate the actual pressure of the gas supply.(d) The gas pressure now decreases by 20 mm

of mercury.

On Fig. 4.1, mark the new positions of the twomercury levels.

47 (a) A man squeezes a pin between his thumband finger, as shown in Fig. 6.1.

The finger exerts a force of 84 N on the pinhead.

The pinhead has an area of 6.0 10 –5 m2.(i) Calculate the pressure exerted by the finger onthe pinhead.(ii) State the value of the force exerted by the pin

on the thumb.

(iii) Explain why the pin causes more pain in theman’s thumb than in his finger.

48 The pressure of a gas is measured using amanometer as shown in the diagram.

The mercury in the manometer is replaced with aliquid which is less dense.How does the value of h change? A It becomes zero.B It decreases, but not to zero.C It stays the same.D It increases.

49 (a) Fig. 4.1 shows end views of the walls builtby two bricklayers.

Which wall is the least likely to sink into the soil,and why?(b) Fig. 4.2 shows two horizontal squares P andQ.

The atmosphere is pressing down on both P andQ.

(i) Name two quantities that would need to beknown in order to calculate theatmospheric pressure on square P.

(ii) The area of P is four times that of Q.Complete the following sentences.


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1. The atmospheric pressure on P is……………………………… the atmospheric pressure on Q.2. The force of the atmosphere on P is……………………………… the force of the atmosphere on Q.

4 What is a simple mercury barometer designedto measure? A the pressure beneath a liquidB the pressure of a gas supplyC the pressure of car tyresD the pressure of the atmosphere

50 A sealed gas cylinder is left outside on a hot,sunny day.What happens to the average speed of themolecules and to the pressure of the gas in thecylinder as the temperature rises?

51 The diagram shows two mercury barometers.Barometer 1 is measuring atmospheric pressureon day 1.Barometer 2 is measuring atmospheric pressure

on day 2.

Which statement is true? A The atmospheric pressure on day 1 is less thanthe atmospheric pressure on day 2.B The atmospheric pressure on day 1 is the sameas the atmospheric pressure on day 2.C The pressure at point X is less than thepressure at point Y.D The pressure at point X is the same as thepressure at point Y.

52 A fixed amount of dry gas is exerting apressure on its container.(a) In terms of molecules, explain what causes thepressure.(b) One of the sketch graphs in Fig. 2.1 showshow the pressure of the gas varies with volume

at constant temperature, and the other shows howthe pressure varies with temperature atconstant volume.The pressure axis has been labelled in each case.

(i) On the appropriate graphs, label one horizontalaxis “ volume / m3 ” and the other horizontal axis “ temperature / °C ”. (ii) On one of the graphs, mark, with the letter X,the pressure of the gas at the ice point.

53 During a period of hot weather, theatmospheric pressure on the pond in Fig. 3.1

remains constant.Water evaporates from the pond, so that thedepth h decreases.

(a) Study the diagram and state, giving yourreason, what happens during this hot period to(i) the force of the air on the surface of the pond,(ii) the pressure at the bottom of the pond.(b) On a certain day, the pond is 12 m deep.

(i) Water has a density of 1000 kg / m3.Calculate the pressure at the bottom of the ponddue to the water.(ii) Atmospheric pressure on that day is 1.0 × 105Pa.Calculate the total pressure at the bottom of thepond.(iii) A bubble of gas is released from the mud at

the bottom of the pond. Its initial volume is0.5 cm3.Ignoring any temperature differences in the water,calculate the volume of the bubble as

it reaches the surface.(iv) In fact, the temperature of the water is

greater at the top than at the bottom of the pond.Comment on the bubble volume you havecalculated in (b)(iii).


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54 Fig. 5.1 shows a gas contained in a cylinderenclosed by a piston.

pressure gauge, is 300 kPa. The area of cross-section of the cylinder is 0.12 m2.(a) (i) Describe the motion of the molecules of thegas.(ii) Explain how the molecules exert a force on

the walls of the cylinder.(iii) Calculate the force exerted by the gas on the

piston.(b) The piston is moved so that the new length of

cylinder occupied by the gas is 50 cm. Thetemperature of the gas is unchanged.(i) Calculate the new pressure of the gas.pressure =(ii) Explain, in terms of the behaviour of themolecules, why the pressure has changed.

55 A chair is placed on protective cups to preventdamage to the carpet underneath it.

How do the cups change the area of contact withthe carpet and the pressure on it?

56 (a) Complete Fig. 4.1 to show a simplemercury barometer. Insert the correct labels in theboxes. Label with the letter h the measurementrequired to calculate the pressure of theatmosphere.

(b) The value of h taken using this barometer is0.73 m. The density of mercury is 13 600 kg / m3.Calculate the value of the atmospheric pressuresuggested by this measurement.Use g = 10 m / s2.(c) Standard atmospheric pressure is 0.76 m of

mercury. Suggest a reason why the value of h in(b) is lower than this.

4 A sealed balloon containing some helium gas isreleased and rises into the upper atmosphere. Asthe balloon rises the temperature of the heliumfalls and the balloon expands.Explain, in terms of atoms,(a) the effect of the fall in temperature on thehelium pressure,(b) the effect of the expansion of the balloon onthe helium pressure.

4 A soldier wears boots, each having an area of0.016 m2 in contact with the ground.The soldier weighs 720 N.(a) (i) Write down the equation that is used to findthe pressure exerted by the soldier on theground.(ii) Calculate the pressure exerted by the soldierwhen he is standing to attention, with bothboots on the ground.(b) The soldier is crossing a sandy desert.

Explain, stating the relevant Physics, why thissoldier is at an advantage over another soldierwho has the same weight but smaller feet.(c) The soldier’s unit is sent to a cold country, andon one occasion he has to cross a frozen lake.Suggest one way that the soldier can reduce therisk of the ice breaking under his weight.

2 Fig. 2.1 shows a simple mercury barometeralongside a mercury manometer that containssome trapped gas.


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From Fig. 2.1 find

(a) the pressure of the atmosphere,(b) the pressure of the trapped gas.(c) The atmospheric pressure increases.

State what happens to the levels of mercury in themanometer.left-hand levelright-hand level

4 Fig. 4.1 represents part of the hydraulic brakingsystem of a car.

The force F 1 of the driver’s foot on the brake pedalmoves piston X. The space betweenpistons X and Y is filled with oil which cannot becompressed. The force F 2 exerted by the oilmoves piston Y. This force is applied to the brakemechanism in the wheels of the car.The area of cross-section of piston X is 4.8 cm2.(a) The force F 1 is 90 N. Calculate the pressureexerted on the oil by piston X.(b) The pressure on piston Y is the same as the

pressure applied by piston X. Explain whythe force F 2 is greater than the force F 1.(c) Piston Y moves a smaller distance than piston

X. Explain why.(d) Suggest why the braking system does not

work properly if the oil contains bubbles of air.

8 The diagram shows a mercury barometer.

Which distance is used to calculate the pressureof the atmosphere? A 25 cm B 75 cm C 80 cm D 100 cm

3 Fig. 3.1 shows a manometer being used tomeasure the pressure of some gas in a container.The container is connected to the manometer by alength of rubber tubing.

(a) State whether the pressure of the gas in thecontainer is greater than, the same as, orless than the pressure of the atmosphere.(b) From Fig. 3.1, deduce the difference between

the gas pressure and the atmosphericpressure.mercury(c) The atmospheric pressure is 752 mm of

mercury.Calculate the actual pressure of the gas in thecontainer.(d) State how the vertical height difference of the

two mercury surfaces changes, if at all, ifa mercury manometer made from a narrower tubeis used.

4 (a) Fig. 4.1 shows some gas contained in acylinder by a heavy piston. The piston can moveup and down in the cylinder with negligible friction.


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There is a small increase in the pressure of theatmosphere above the piston.(i) On Fig. 4.1, draw a possible new position forthe lower face of the piston.(ii) Explain, in terms of the molecules of the gasand the molecules of the atmosphere,your answer to (a)(i).(b) The pressure of the atmosphere above the

piston returns to its original value, and thepiston returns to its original position, as shown in

Fig. 4.2.

The gas, piston and cylinder are now heated to amuch higher temperature.(i) On Fig. 4.2, draw a possible new position forthe lower face of the piston.(ii) Explain, in terms of the molecules of the gasand the molecules of the atmosphere,your answer to (b)(i).

IGCSE PHYSICS ON 2002 TO ON 2012

191234098 Pressure Questions for IGCSE Physics

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