125125125

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6CHAPTER

1266.1 LO • Explain the existence of air pressure with reference to the

Kinetic Theory

To show that air exerts pressure

Drinking glass, thick cardboard, water

1 Fully fill a glass with water and press a piece of thick cardboard on the surface of thewater.

2 Invert the glass without removing your hand from the cardboard.3 Release your hand from the cardboard that supports the water.4 Record your observations.

Water in the glass .

1 What acts on the thick cardboard to support the water in the glass?Air pressure

2 In the diagram below, draw an arrow (→) to show the direction of air pressure actingon the cardboard.

Air exerts .pressureCONCLUSION

glass

waterthick

cardboard

ANALYSIS

did not spill outOBSERVATION

glass

cardboard

water

PROCEDURE

MATERIALS

AIM

6.1 Air pressureInquiry-DiscoveryEXPERIMENT

INQUIRYLearning Objective 6.1 Understanding air pressure

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CHAPTER6

1276.2 LO • Explain the existence of air pressure with reference to the

Kinetic Theory

To determine the factors that influence air pressure

Balloon, rubber band, dented ping-pong ball, hot water

Glass

1 Blow up a balloon and tie its mouth tightly with a rubber band.2 Press hard on both sides of the balloon with your hands as shown in Diagram (a) and record

if you can feel the pressure inside the balloon.3 Put a dented ping-pong ball into hot water as shown in Diagram (b) and record your

observation.

OBSERVATION

PROCEDURE

APPARATUS

MATERIALS

AIM

Diagram (a) Diagram (b)

1 What happens to the volume of air in the balloon when it is pressed?Decreases

2 How is the air pressure influenced by the volume of air?

The the volume of air, the the air

pressure.

3 What happens to the air particles in the ping-pong ball when it is heated?

The air particles move and

with the wall of the ping-pong ball.

4 What is the effect of heat on the air pressure in the ping-pong ball?

The air pressure in the ping-pong ball when the

ball is .

The pressure of air is influenced by the and of the air.temperaturevolumeCONCLUSION

heated

increases

collide more frequentlyfaster

highersmaller

ANALYSIS

dentedping-pongball

glass

hot water

6.2 Factors that influence air pressureInquiry-DiscoveryEXPERIMENT

INQUIRY

Atmospheric pressurechanges widely on theEarth.These variations arethe fundamental instudying weather andclimate.

TSTS• Relating

TSTS• Relating

Activity Observation

1 Balloon is pressed. inside the balloon is felt.

2 Dented ping-pong ball is putinto hot water.

The ping-pong ball becomes .spherical again

Pressure

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6CHAPTER

1286.3 LO • Explain with examples things that use the principle of air

pressure6.4 LO • Generate ideas to solve problems using the principle of air

pressure

Symbols

• L.P. – lower air pressure region• H.P.– higher air pressure region• ↓↓ – action of air pressure

(if operating)1 Siphon

2 Syringe

3 Drinking straw 4 Pouring liquids from a can

5 Suction pump 6 Dropper

waterL.P.

H.P.

water

water is sucked up

L.P.H.P.

water

piston

L.P. H.P.

L.P.

H.P.

H.P.

L.P.

dirt

rubber teat

L.P.

H.P.

Mark the following symbols on theinstruments which make use ofthe principle of air pressure.

6.3 Air pressure

Learning Objective6.2 Applying the principle of air pressure

DISCUSSIONActivity Contextual

Study the laboratory activity below and draw the expected observation in the box provided. Then, fill inthe blanks with the suitable words.

heat

water

cold water is pouredonto the can

stopper

The air pressure inside the can is

. The

air pressure outside the can,

the can. This

activity shows that air exerts

.pressure

compresses

higherreduced

6.4 Application of the principle of air pressureSTSActivity

THINKING

higher compresses reduced pressure

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CHAPTER6

129

Dear students,

This section contains questions withfrequently asked concepts and facts in the PMR examination. Master theseconcepts and facts by answering the following questions.

1 Draw the direction of the air pressure that 2 Draw the observation of the following experiment.acts on the cardboard.

Diagram 1 Diagram 2

3 Air pressure in a closed container will increase 4 State factors that influence gas pressure.when,

(a) the number of gas particles (increase, decreases). (a)

(b) the volume of the container (increases, decreases). (b)

(c) the gas is (heated, cooled).

5 Name these devices. Mark ‘H’ to show high pressure area and ‘L’ to show low pressure area.

(a) (b) (c) (d)

Diagram 3

6 Complete the following statement.

Gas will change to liquid if it is or placed under

, such as in a gas cylinder.high pressure

cooled

The temperature

The volume of gas

glass

water

cardboard

H

Syringe

LH

Drinkingstraw

L

H

Siphon

L

H

Suctionpump

H

L

dirt

heat

cold water

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6CHAPTER

130

1

Diagram 1

When air is blown into the rolled-uppaper tube, the tube straightens outas shown in Diagram 1. At which ofthe points K, L, M, and N is the airpressure highest?A K C M

B L D N

2 A dented ping-pong ball becomesspherical again when it is put intohot water. This is becauseA the wall of the ping-pong ball

expandsB the pressure inside the ping-pong

ball increasesC the ping-pong ball reacts with

cold airD the air pressure outside the ping-

pong ball is higher than thatinside it

3 The pressure of a gas inside acontainer can be reduced by

I increasing the volume ofcontainer

II decreasing the amount of gasIII cooling the containerA I and II onlyB I and III onlyC II and III onlyD I, II and III

4

Diagram 2

Of the holes at K, L, M, and N shownin the diagram, which hole preventswater from being sucked out of thebeaker?

I K

II L

III M

A I and II onlyB I and III onlyC II and III onlyD I, II and III

5 A gas can be changed to liquid stateby

I cooling itII compressing it

III boiling itA I and II onlyB I and III onlyC II and III onlyD I, II and III

6

Diagram 3

Among the directions A, B, C and D,which is the direction of air pressurethat supports the cardboard and theglass?

7

Diagram 4

Of the points A, B, C, and D, which isthe area of low pressure to enablewater to be sucked into the syringe?

8

Diagram 5

Diagram 5 shows an experiment onair pressure. When the piston ispushed in, the balloon contracts.This is becauseA the air pressure at P is lower

than the air pressure at RB the air pressure at P is equal to

the air pressure at QC the air pressure at Q is lower

than the air pressure at RD the air pressure at Q is higher

than the air pressure at P

9

Diagram 6

Which of the following P, Q, R and S,are areas of low pressure and highpressure to enable the dirt to beremoved from the clogged pipe?

Low High

pressure pressure

A P Q

B P S

C R Q

D Q S

10 Among the following, what happensto the gas particles in a closedcontainer that is being cooled?A Size increasesB Mass decreasesC Move more slowlyD Hit the walls more often C

D

suction pump

dirt

Q

P

RS

D

balloon

piston

push in

syringe

R P

Q

B

water

piston

syringeA

B

C

D

C

glasswater

D

B

C

A

thick cardboard

A

A

beaker

water

L

K

M

sucked

D

B

C

air is blown

K L M

N

CLONE2006

PMRPMRPMR 66EnhancementCorner

Paper 1Each question is followed by four options A, B, C and D. Choose the best answer.

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CHAPTER6

131

1

The figure above shows an activity to study air pressure.

(a) What will happen if the hand X is removed?

The water remains in the can/The water does not spill out

(b) Draw an arrow (:) in the diagram below to show the direction that air pressure acts on the cardboard.

(c) What conclusion can be made from this activity?

Air exerts pressure

2

The diagram above shows an experiment carried out to study the effect of air pressure.

(a) What can you observe after awhile?

The plastic bottle becomes dented.

(b) Give an inference to your answer in (a).

The air pressure inside the bottle is reduced.

(c) Mark X in the diagram above to show the location of lower air pressure.

(d) Draw arrows (→) in the diagram above to show the action of air pressure on the plastic bottle.

Section AAnswer all the questions.

Paper 2

to filterpump

airX

plasticbottle

←

→

→

→

→

→

PMR 6X

→

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