soalan dan kuiz pressure

7/27/2019 Soalan Dan Kuiz Pressure

http://slidepdf.com/reader/full/soalan-dan-kuiz-pressure 1/11

3.11. A metal block of density 2700 kg m-3 and dimensions 20cm ×50cm ×4cm

is placed on a table as shown in Figure 1.1

Figure 1

Calculate the(i) weight, = mg

N

g

108

1010450202700

=

×××××=

= ρυ

(ii) minimum pressuremax

A

mg =

2

4

1080

105020

108

−

−

=

××

=

Nm

(iii) maximum pressure of the metal blockmin

A

mg =

2

4

13500

10420

108

−

−

=

××

=

Nm

3.32 The diagram shows a manometer which is connected to a gas supply. The

atmospheric pressure is 76 cm Hg

50cm

20cm

4cm



Figure 2

(a) What is the pressure at the point A?

76 cm Hg

(b) Find the pressure of the gas supply,Pressure of gas supply = (76+30) cm Hg = 106 cm Hg

(c) The tap is opened and the mercury is allowed to flow out until the level Bfalls to the division 60 cm of the ruler. State the new position of level A.

At division 30 cm

3.33. Figure 2.1 shows the arrangement of the apparatus in an experiment to study

the pressure of moving air



Figure 3

(a) Situation I : No air enters the glass tube.i) How are the levels of mercury in both parts of the U-tube?

Same

ii) Explain your answer The pressure in both columns is the same

(b) Situation II: When air flows into the glass tube, the difference in the levelsof mercury at P and Q is shown in Figure 2.1. Calculate the air pressure atP.[Atmospheric pressure = 76 cm Hg]Pressure at P = 76-5 cm Hg

= 71 cm Hg

(c) Figure 2.2 shows a soft toy hanging from a sucker which is fixed to a glass

wall.How is the sucker fixed to the glass wall?The air in the rubber sucker is a partial vacuum, therefore theatmospheric pressure is higher than the pressure in the sucker

3.3



Figure 4

4. Figure 4 shows an apparatus used in the laboratory to measureatmospheric pressure. The length of the glass tube is 100 cm. The heightof the vacuum column is 8 cm and the height of the mercury column is 76cm.

(a) Name the apparatus as shown in the figureSimple mercury barometer

(b) (i) What is the value of the atmospheric pressure in cm Hg?76 cm Hg

(ii) What is the pressure at point X in cm Hg?76 cm Hg + 16 cm Hg = 92 cm Hg.

(iii) If the density of the mercury is 1.36 × 104 kg m-3 and theacceleration due to gravity is 9.8 ms-2.Calculate the atmospheric

pressure in pascal. Atmospheric pressure

Pa

gh

5

4

1001.1

)76.0)(8.9)(1036.1(

×=

×=

= ρ

(c) What will happen to the height of mercury column from the surface of the mercury in the container if (i) the tube is raised through a height of 12 cm?

Fixed at 76 cm Hg

(ii) the tube is lowered through a depth of 6 cm?Fixed at 76 cm Hg

(iii) the glass tube is inclined about 2o from the vertical line?Fixed at 76 cm Hg

(iv)Give reason for you answer in (c) (iii)



Upper region of the tube is still vacuum, the height of themercury column or the atmospheric pressure still does not change

(d) The apparatus above can be used to measure altitude

(i) Explain why this can be done At higher altitude, the atmospheric pressure decrease and thiscauses the height of the mercury column to decrease

(ii) Explain why the apparatus above is not suitable to measure altitudeThis instrument is too long and is difficult to carry from one

place to another place.

3.25. (a) Figure 3.1 shows a mercury manometer connected to a gas X and figure3.2 is mercury manometer connected to a gas Y.

(i) Define pressure.Pressure is the force per unit area.

(ii) Calculate the pressure of gas X in Nm-2 ?Pressure of gas X = 76 + 14

= 90 cm HgPX = h ρ g

= 0.90 x 1.36 x 104 x 10= 1.22 x 105 Nm-2

(iii) Calculate the pressure of gas Y in Nm-2 Pressure of gas Y = 76 - 8

= 68 cm HgPY = h ρ g

= 0.68 x 1.36 x 104 x 10= 9.24 x 105 Nm-2

(b) Figure 3.3 shows an U-tube contains water and a liquid Q which areseparated by mercury. The mercury surfaces on the two arms are at thesame level.



(i) Why the surface of the mercury in the two arms are at the same level. ?Because the two surfaces are at the same pressure.

(ii) Calculate the pressure at X due to the water column.Pressure due to water at X = h ρ g= 0.38 x 1000 x 10= 3.8 x 103 Nm-2

(iii) What is the pressure at Y due to the liquid Q ?Pressure due to water at Y = Pressure due to water at X

= 3.8 x 103 Nm-2

(iv) Calculate the density of the liquid Q ?Using h 1ρ1 = h2 ρ2

38 x 1000 = 43 x ρ2

ρ2 = 884 kg m-3

(d) Figure 3.4 shows the mercury tank of a mercury barometer being placedin a bigger water tank. The water surface is 40 cm above the mercurysurface in the mercury tank. ( Atmospheric pressure = 76 cm Hg ).



(i) What is the pressure at X in cm Hg ?76 cm Hg.

(ii) What is the pressure at Y due to water in cm Hg ?h 1ρ1 = h2 ρ2

h 1 x 13.6 = 40 x 1h 1 = 2.9 cm

(iii) What is the total pressure at Y in cm Hg ?P = 76 + 2.9

= 78.9 cm Hg.

(iv) What is the value of h ?h + 40 = 78.9

h = 38.9 cm



3.11. A metal block of density 2700 kg m-3 and dimensions 20cm ×50cm ×4cm

is placed on a table as shown in Figure 1.1

Figure 1

Calculate the(i) weight, = mg

(ii) minimum pressure

(iii) maximum pressure of the metal block

50cm

20cm

4cm



PHYSICS FORM FOUR

FORMATIVE QUIZ

3.1 : PRESSURE

1. Pressure is defined as

A. force per unit area C. Force per unit lengthB. mass per un it area D. mass per unit volume.

2. The diagram shows an elephant weighing 42 000 N stands on one foot of area 1000 cm -2 .

What pressure exerted on the ground by the elephant ?

A. 42 Pa C. 42 kPa

B 420 pa D. 420 kPa

3. A block resting on a floor has a contact area of 400 cm -2 . If The pressure exerted by a blockon the floor is 5 kPa, what is the mass of the block ?[ g = 10 m s-2 ]

A. 10 kg C. 30 kgB. 20 kg D. 40 kg

4. Which of the following is not an application of high pressure ?

A. Studs on the soles of a pair of bootsB. The sharp edge of a knife use for cutting purposesC. Hammering a nail with a sharp end into a wall

D. Military tanks having special wheel called caterpillar track.

5. Which shoe would exert the greatest pressure on the ground when worn by the same lady ?

Name : Class : 4



PHYSICS FORM FOUR

FORMATIVE QUIZ

3.2: PRESSURE IN LIQUID

1. Which of the following factors does not influence the pressure of a liquid ?A. Depth C. VolumeB. Density D. Acceleration due to gravity

2. Liquids P and Q are stored in large open tanks. Liquid P and Q have densities 800 kg m-3 .and 1000 kg m -3 .respectively. At what depths are the pressures equal ?

Depth in liquid P Depth in liquid Q

A 4 m 5 m

B 5 m 4 m

C 3 m 3 m

D 2 m 2 m

3. The diagram shows a tall cylinder containing oil.

Density of the oil is 850 kg m -3 .The pressure exerted by the oil at X is

A. 0.51 x 104

Pa C. 1.53 x 104

PaB. 1.02 x 104 Pa D. 1.00 x 104 Pa

4. The diagram shows a U-tube containing water and a liquid X.[ Density of water = 1000 kg m -3 ]

The density of a liquid X isA. 1148 kg m -3 C. 2642 kg m -3

B. 1428 kg m -3 D. 2851 kg m -3

5. For the same depth, which of the following liquid has the highest pressure at its base ?

A. water C. MercuryB. Alcohol D. Oil

Name : Class : 4



PHYSICS FORM FOUR

FORMATIVE QUIZ

3.3: GAS PRESSURE AND ATMOSPHERIC PRESSURE

1. Which of the following is not a measurement of atmospheric pressure ?

A. 76 cm Hg C. 1.02 x 105

N B. 10 m water D. 1 bar

2. Gas trapped in a closed container. There exists gas pressure inside thethe container because gas moleculesA. move randomly C. collide with one another

C. move with equal speed D. collide constantly with the walls of container

3. The diagrams shows a gas being trapped by a mercury column in a tube immersed in aa container containing mercury. [ Atmospheric pressure = 76 cm Hg]

The pressure of the gas is

A. 14 cm Hg C. 76 cm HgB. 62 cm Hg D. 138 cm Hg.

4. Figure below shows a U-tube filled with mercury.

One end of the U-tube is connected to a gas supply of pressure p whereas another end is he a

exposed to air. Given that the atmospheric pressure is 76 cm Hg.Which of the following statements is not true ?

A. Pressure p is 72 cm Hg C. Pressure p is 80 cm Hg.B. Pressure at point C is 76 cm Hg. D. Pressure at point A equals to pressure at point B

5. Which of the following instrument is used to measure atmospheric pressure ?

A. Aneroid barometer C. ManometerB. Bourdon Gauge

Name : Class : 4

soalan dan kuiz pressure

Documents