1.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
31
U N D E R S T A N D I N G P R E S S U R E
Define pressure. Pressure is defined as the __ force __ applied on a unit __ surface area __.
P =
A
F
1 Pa = __1_ N m2
Example : The diagram shows a wooden block of dimensions 8 cm × 10 cm ×
12 cm. Its weight is 12 N. On which side should the wooden block
be placed to produce a maximum pressure exerted on the table.
What is value of this pressure ?
P = Weight (F) .
Minimum Area (A)
= ___12____
(0.08)(0.10)
= 1500 Pa
Problem Solving 1. Calculate the pressure on a wall when the palm of a hand with area 150
cm2
is pushed against the wall a force of 210 N.
P = F/A = 210 / 150
= 1.4 N cm2
2. A teacher who weights 637N has a foot with a surface area of 200 cm2
.
When he stands with one foot, calculate the force applied.
P = F/A = 637 / 200
= 3.185 N cm2
Relationship between
pressure and force,
pressure and surface
area
Situation 1 : Figure 3.1a, press a thumbtack into a piece of wood with your
thumb where as Figure 3.1b, hit using the hammer.
Figure 3.1(a) Figure 3.1(b)
(a) Observe Figure 3.1a and Figure 3.1b and state one comparison.
___ Figure 3.1 (b) sink deeper compare to Figure 3.1(a).__
F = Force (N)
A = surface area (m
2
)
P = Pressure (__Pa)
3.1
2.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
32
(b) Which one is received a higher force?
____ Figure 3.1(b) received higher force.____
(c) State the relationship between pressure and force.
The pressure produce increases with force applied .
Situation 2 : A 500 g cardboard box placed on a table in two different
orientations.
Figure 3.2a Figure 3.2b.
(a) Calculate the pressure exerted on the table for
i) figure 3.2a ii) figure 3.2b.
5 / 12 x 20 5 / 10 x 20
= 0.028 N cm2
= 0.025 N cm2
(b) Which figure shows that the higher pressure is exerted to the table?
__ figure 3.2(b)_
(c) State the relationship between pressure and surface area.
____ Pressure is inversely proportional to the surface area.__
Factor that affecting
pressure.
 Force
 Surface Area
1. Ways to increase pressure are :
a)__increase _force ; b) __decrease __area of contact.
2. Ways to decrease pressure are :
a) ___ decrease __force ; b) __ increase _area of contact.
The applications of
pressure in our daily
life.
a) High pressure.
Tools like knives, chisels, axes and saws have sharp cutting edges. The
surface area of contact is _small_ When a force is applied on the tool, the
small area of contact will produce a _ higher__ pressure to cut the
material.
3.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
33
b) Low pressure.
The flat base of each metal pole of a tent has a __big__ surface area to
_reduce_ the pressure exerted on the ground. The poles will not sink
into the ground because of the flat bases.
Exercise
1. A cylinder has a mass of 12 kg and a
crosssectional area of 200 cm2
. What
is the pressure acting at its base?
A. 6 kPa B. 9 kPa
C. 12 kPa D. 15 kPa
2. Wind blows normally on a wall at a
pressure of 200 kPa. If the wall has
an area of 5 m2
., what is the force
acting on the wall?
A. 40kN B. 800kN
C. 1000KN D. 1200kN
3. A 250 N force is applied at an angle 30o
to the
surface of a block. The surface is a square of
sides 10 cm. What is the pressure exerted on
the surface?
A. 1.25 kPa B. 2.50 kPa
C. 25.0 kPa D. 12.5 kPa
4. A balloon is pressed with a force of 2.4 N
using a finger. Find the pressure exerted on
the balloon if the area of fingertip is 2.0 x
104
m2
P = F/A = 2.4 / 2 x 104
= 12 000 Pa
5. The diagram below shows a concrete block of dimension 1.5 m x 2.0 m x 3.0 m.
Its weight is 60N. Calculate (a)maximum pressure, (b)minimum pressure:
a) maximum pressure b) minimum pressure
= 60 / 2.0 x 1.5
= 20 Pa =60 / 2.0 x 3.0
= 10 Pa
4.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
34
6. A Perodua Myvi with a mass of 900 kg. Air pressure for each tyre is 2 x 105
Pa.
(a) What is the meaning of pressure ?
___ force exerted per unit area.___
(b) Calculate the area in contact with the ground for each tyre.
A = (9000 / 4) / 2 x 105
= 0.01125 m 2
c) Zamani drives his car to his school with a distance of 10 km and find his car tyre become harder
than usual. Explain why this is happen?
________ pressure increase with temperature____
________________________________________________________________________
7. Experiment : Based on the diagram below, complete the suitable planning experiment.
a) Inference :… Pressure produce depends on surface area.…
b) Hypothesis :… The bigger the surface area, the lesser the pressure produced……
c.i) Aim :… To investigate the relationship between surface area and pressure. ……
ii) Variables i) Manipulated : … surface area , A …………………………
ii) Responding : … the depth of wood sink in plasticine, P (pressure)
iii) Constant : … Force applied ( mass of weights )………
iii) Apparatus
& material
…… placticine, 100 g metal weights, wooden support , wooden disc (different
sizes ) and ruler…….
5.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
35
iv) Diagram
~~ same as diagram in the question ~~
v) Procedure …1. The wooden disc with surface area 2 cm2
is put under the wooden
support.
2. Placed 100 g metal weight on the top of wooden rod as shown in diagram
above.
3. Measured the depth of wooden sinks in the plasticine using the ruler
4. The experiment is repeated using different sizes of wooden disc, 4 cm2
, 6
cm2
, 8 cm2
and 10 cm2
.
vii) Result
A / cm2
2 4 6 8 10
P / cm
viii Analyse
data P/ cm
A/ cm2
6.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
36
UNDERSTANDING PRESSURE IN LIQUIDS
Characteristics
of pressure in
liquid
1. Pressure in liquids acts in _ all _ directions.
2. Draw the jet of water.
3. Draw the water level in the container.
diagram ( All water level are same.)
4. The hole in both containers are at the same height. Draw the jet of water and oil.
 The higher the density the _ higher __ the pressure.

Shape and size _ does
not___ influence the
pressure
Pressure in liquids _
increase __ with depth.
water
oil
3.2
7.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
37
Formula for
pressure in
liquid
The pressure in a liquid is the product of depth, density and gravitational acceleration.
P = x x
P = h x ρ x g
Example :1. An air bubble is at a depth of 5 m below the surface of a lake . What
is the pressure of water on the bubble if the density of the water is
1000 kg m3
?
P = h ρ g
= 5 x 1000 x 10
= _50 000_ Pa
2. The figure shows a high tin with a length of 100 cm is filled to the full
with water.
If the pressure caused by the water at point P is 8000 Pa, What is the
value of L?(Density of water = 1000 kg m  3
)
h = 8 000 / ( 1000 x 10 )
= 0.8 m = 80 cm
l = 100 – h = 20 cm
Experiment : Pressure and density in liquids
a. Inference :…………………………………………………………………………………………
b. Hypothesis :…………………………………………………………………………………………
c. Aim :…………………………………………………………………………………………
d. Variables i) Manipulated : ……………………………
ii) Responding : ……………………………
iii) Constant : ……………………………
P = Pressure ( Pascal)
ρ = density ( _ kg m3
_)
g =__ N kg1
____
h = height (m)
8.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
38
e. Apparatus
& material
…………………………………………………………………………………………
…………………………………………………………………………………………
f. Procedure …………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………………………
………………………………………………………………………………………….
g. Result
h. Analyse
data
: Graph of ……………………………………………………………………………..
………………………………………………………………(draw on graph paper )
i. Conclution :…………………………………………………………………………………………
………………………………………………………………………………………….
j. Precaution :…………………………………………………………………………………………
………………………………………………………………………………………….
Applications of
pressure in
liquid
1. 2.
9.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
39
Exercise
1.
2.
Which of the following factor does
not influence the pressure of a liquid?
A. Depth
B. Acceleration due to gravity
C. Density
D. Volume
Mercury has density of 13600 kg m3
.
If the pressure of mercury is 650 kPa,
what is the depth from its surface?
A. 4.0 m B. 4.8 m
C. 5.8 m D. 6.4m
4.
The density of water is 1000 kg m3
.
Find the density of liquid X in kg m3
?
Px = Pwater
hx x ρx = hwater x ρwater
6 ρx = 2 x 1000
ρx = 333.33 kg m3
3. Water has density equals to 1 g cm3
.
What is its pressure at a depth of 12 m
from the surface?
A. 80 kPa B. 100 kPa
C. 120kPa D. 140kPa
5.
A container contains two layers of liquids. An oil layer 45cm thick floats on 60 cm of water. The
densityof oil is 750 kg m3
and water is 1000 kg m3
. ( g = 10 m s2
)
a) What is the pressure exerted on water by the oil layer?
Poil = h x ρ x g = 3375 Pa
b) what is the total pressure exerted on the bottom of the container?
PT = Poil + Pwater = 9375 Pa
6. The pressure at the bottom of the dam is 2.4 x 106
Pa. What is the depth of water if the density of
water is 1 000 kg m3
.
h = 2.4 x 106
/ ( 1000 x 10 ) = 240 m
10.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
310
7. Figure below shows a crosssectional area of the structure of a dam.
Observe the thickness of the wall at the top and bottom part of the dam in the figure above.
Based on the observations:
(a) State one suitable inference that can be made. [ 1 mark ]
(b) State one appropriate hypothesis for an investigation. [ 1 mark ]
(c) With the use of apparatus such as a thistle funnel, beaker and other apparatus, describe
an experimental framework to test your hypothesis.
In your description, state clearly the following:
(i) aim of the experiment,
(ii) variables in the experiment,
(iii) list of apparatus,
(iv) arrangement of the apparatus,
(v) the procedure of the experiment which include the method of controlling the
manipulated variable and the method of measuring the responding variable,
(vi) the way you would tabulate the data,
(vii) the way you would analysis the data. [ 10 marks ]
( Experiment thistle funnel – density & depth )
WaterWall
11.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
311
U N D E R S T A N D I N G G A S P R E S S U R E A N D
A T M O S P H E R I C P R E S S U R E
Kinetic molecular
theory
Gases are :
Made of … tiny particles ………………………………..
Move … at random …………………………………..
Far apart with a very … weak / low force of….. attraction
Collide each other and collide with the wall of container with …high
energy/speed…
The average kinetic energy ……… increases …when the temperature
…increases…………….
Gas Pressure The gas pressure in a container is caused by the … collision ... of gas molecules
with the …wall… of the container.
Gas pressure can be measured by using 2 types of instrument known as :
(a) . bourdon gauge . gauge (consists of a semicircular or Cshaped copper
tube that tends to straighten if more and more gas is pumped (compressed) into
it).
(b) … manometer…. (consists of a Utube about 1 m in height. About 50% of
the volume of the Utube is filled with liquid such as mercury or water).
Atmospheric
pressure
The atmospheric pressure is caused by the downward … force .. exerted by the
air ( the weight of the atmosphere) on the Earth’s surface.
The greater … the distance … from the sea level, the …lower .. will the
atmospheric pressure.
The atmospheric pressure at sea level is 1 atmosphere ( 1 atm)
1 atmosphere(atm) = …760.. mm Hg = …105
…..Pa = 1000 milibar
Find this:
If density,ρ of mercury (Hg) = 13600 kg m3
and density of water = 1000 kg m3
.
1 atm = __10.336___ m of water
Barometer is an instrument to measure atmospheric pressure. There are 2 types
of barometer:
(a) .... barometer aneroid....... (is made of a partially vacuum sealed metal box).
(b) … simple barometer …. (is made of a long glass tube about 1 meter in length
fully filled with mercury and then inverted (turned upside down) into a bowl of
mercury).
3.3
12.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
312
Example 1: The atmospheric pressure is 760 mm Hg. What is the value of the
atmospheric pressure in Pascal? [ Density of mercury, ρ (Hg) = 13 600
kg m3 ]
h = 760 mm = 76 cm = 0.76 m
Atmospheric pressure, Patm = h ρ g = (0.76)(13600)(9.8)
= …103360 …. Pa
Manometer
1
2
3
h
PA = PB = Patm = 76 cm Hg
PC = PA + PHg PD = PA + PHg
= (76 + 4) cm Hg = 79 cm Hg
= 80 cm Hg
ρHg = 13600 kg m3
; ρwater = 1000 kg m3
PA = PB = Patm = 76 cm Hg
PC = PA + PHg PD = Pc = 80 cm Hg
= (76 + 4) cm Hg = 1088 cm water
= 80 cm Hg
PA = Patm = 76 cm Hg
PC = PA + PHg
= (76 + 4) cm Hg
= 80 cm Hg
Pgas = PD = Pc
= 80 cm Hg
13.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
313
Simple Barometer 1. Figure shows apparatus set up
which is used to measure
atmospheric pressure.
[Mercury density = 1.36 x 104 kg m
3
]
Calculate the pressure at point Q in
Pa.
2. If the atmospheric pressure is 76
cm Hg, what is the pressure of the
trapped air P?
Applications of
atmospheric
pressure.
1.Siphon
2. Vacuum cleaner
………………………………….
…………………………………..
…………………………………..
…………………………………..
…………spm 2009……
…………………………………..
…………………………………..
…………………………………..
14.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
314
Exercise ( g = 9.8 m s2
; ρHg = 13.6 x 103
kg m3
)
1. What is the pressure of the gas
trapped inside the Jtube, in Pa unit?
A. 1.19 x 105
Pa
B. 1.90 x 105
Pa
C. 2.19 x 105
Pa
D. 2.90 x 105
Pa
2.
3.
Which instruments is meant for
measuring atmospheric pressure?
A. Carburettor
B. Siphon
C. Fortin’s Barometer
D. Hydrometer
Which of the following is not true about
atmospheric pressure?
A. Atmospheric pressure acts in all
directions.
B. Atmospheric pressure decreases with
distance from Earth’s surface.
C. Atmospheric pressure can only measure
in Pa or N m2
.
3 Diagram below shows a set up of apparatus for measuring atmospheric pressure.
Diagram shows a set up of apparatus for measuring atmospheric pressure.
(a) What is the name for the instrument?
… Simple Barometer ……………………………………………………………………
(b) Determine the atmospheric pressure as measured by the instrument ,
(i) in the cm Hg unit (ii) in the Pa unit
76 cm Hg = 0.76 x 13600 x 9.8
= 101292.8 Pa
(c) State the change of length of the mercury column above the mercury surface
(i) The tube is raised by 10cm ...…… unchanged ………………………………….
(ii) The surrounding temperature increases ………… decrease …………………..
(iii) The instrument is brought to the peak of a mountain …… decrease …………..
(iv) Water vapor is brought to the vacuum region ……… decrease ..……………
15.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
315
P A S C A L ’ S P R I N C I P L E
Definition Pascal’s Principle state that pressure exerted on an … enclosed …fluid is transmitted
…… equally in all direction …. to every part of the fluid.
Water spurts out at the _ same ______
speed because the pressure act at
all the point are …same….
Pascal’s
Principle
Remember,
P = F
A
Pressure at both side are same, PA = PB
So that ; FA = FB
AA AB
a) When 20 N of force is applied at piston A, FB produced is
FB = FA AB = 20 x 8.0 FB = _400 N ___
AA 0.47
b) When piston A is moved downward for 2 m, how far the load has been move up.
Volume of liquid transmitted from A to B are equal.
VA = VB ; where as V = Ah
AAhA = ABhB
hB = __0.1 m __
A B
3.4
16.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
316
Application
of Pascal’s
Principle
Gather information about ;
1. Hydraulic brake system
2. Automobile hydraulic lift.
Exercise
1. Figure below shows a hydraulic jack.
Piston A and piston B have cross
sectional areas 5 cm2
and 100 cm2
respectively. If mass of 3kg is placed
on piston A, what is the maximum
weight that can be lifted by piston B?
A. 300N B. 600N
C. 800N D. 900N
2.
3.
Which of the following device is
based on the Pascal’s Principle of
pressure transmission?
A. Hydrometer
B. Car’s hydraulic brake
C. Bunsen burner
D. Fire extinguisher
The input piston of hydraulic press is
pushed down 2.0 cm from the original
position. If the cross sectional area of
input piston is 5.0 cm2
and of the
output piston is 50 cm2
, how much
will the load be raised up?
A. 0.2 cm B. 1.0 cm
C. 1.5 cm D. 1.8 cm
4 A hydraulic jack which is used for lifting a car at a service centre for motor vehicles. The
hydraulic jack made up of two pistons X and Y of crosssectional area 0.02 m2
and 18 m2
respectively. When the compressor is switched on, a force of 200 N acts on piston X.
(a) Name the physics principle applied in the hydraulic jack.
__ Pascal’s principle _______________________________________
(b) Explain how the car is lifted
__when piston X is pushed down. The pressure exerted is transmitted equally to the
piston Y. the big force produced then push the car upward._________
17.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
317
(c) State two advantages of using oil as the hydraulic fluid of water.
__cannot be compress ; reduce friction. _____________
(d) Calculate the pressure exerted on piston Y.
10 000 Pa
(e) Calculate the maximum weight of a load that can be lifted by piston Y.
180 000 N
(f) If piston X move down by 45 cm, what is the distance moved by piston Y?
0.05 cm
5. Cross section area of piston A and piston B are 4000 cm2
and 6 000 cm2
respectively.
i) Calculate the ratio of the force acting on piston A with the force acting on piston B
2 : 3
ii) If the piston B lifts a car 2.50 m high, how far to the right should piston A move?
3.75 m
iii) Why the system less effective when there is air bubbles in the piston.
… some force are used to press the air bubbles.…….
6. Given that the crosssectional area of smaller piston and larger piston are 20 cm2
and 60 cm2
respectively. If the smaller piston is pushed with a force of 15 N.
Calculate;
a) i) Pressure exerted on smaller piston. ii) Pressure exerted on larger piston
15 / 20 = 0.75 N cm2
PL = Ps = 0.75 N cm2
b) the ratio of pressure acted on the smaller piston and larger piston
1 : 1
c) the force experienced by the larger piston
FL = 0.75 x 60 = 45 N
18.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
318
A R C H I M E D E S ’ P R I N C I P L E
Definition Archimedes’ Principle: When an object is __ fully __ or __partially __ immersed in a
fluid, the upthrust or ___buoyancy __ on it is equal to the __weight __ of fluid displaced.
Relationship
between ;
1. FB with
liquid
displaced
2. FB with
Weight of
floating
object
Simple activity to show the presence of buoyant force
1. Determine the actual weight of plasticine and the apparent weight of the plasticine
in water.
Actual weight = ………………………
Apparent weight = ………………….
(The weight of plasticine in water)
Loss in weight = …………………….
Weight of = Buoyant force
Water Displaced
Volume of liquid displaced = Volume of _ object immersed
2. Floating object
Buoyancy
Force, FB
FB = buoyant force (N)
FB = Wliquid displaced ; W = mg ; m = V ρ ρ = density (kgm3
)
g = 10 ms2
FB = __ Vρg __ V = volume (m3
)
Example 1. An object of density, 40 g cm3
and mass 500 g is immersed in a liquid of density
2 g cm3
. Calculate;
a) the volume of liquid displaced b) the mass of the liquid displaced
Floating Buoyant force = weight of object
F
W
3.5
19.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
319
V = 500 / 40 = 12.5 cm3
m = 2 x 12.5 = 6.25 g
c) the buoyant force experienced by the object (g =10 m s2
)
FB = 0.0625 N
Application
of
Archimedes’
Principle
1. Submarine
2. Hot Air Ballon
3. Hydrometer
Exercise
1. A ship of mass 80000 kg floats on the
sea surface. If the density of the sea
water is 1250 kg m3
, what is the
volume of the displaced sea water?
A. 6.4 m3
B. 64 m3
C. 640 m3
D. 800 m3
2. The diagram shows an object partly floated and
immersed in a liquid. What was the mass of the
object. ( g = 10 m s2
)
A. 2.0 N B. 20 N
C. 0.020 kg D. 200 g
3. The diagram shows an object immersed
in two liquids of different densities.
Which of the following related F1 and F2
correctly?
A. F1 < F2 B. F1 = F2 C. F1 > F2
4. A body of density 800 kg m3
floats in liquid A
and liquid B as shown. If the density of liquid B is
1000 kg m3
, what is the possible density of
liquid A?
A. 790 kg m3
B. 905 kg m3
C. 1000 kg m3
D. 1050 kg m3
20.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
320
5. (a) A fisherman finds that his boat is at different levels in the sea and in the river, although
the boat carries the same load. The density of sea water is 1 025 kg m3
and of river water
is 1 000 kg m3
.
Figure 1 and 2 illustrate the situation of the boat in the sea and in the river.
(i) What is meant by density?
___________________________________________________________________
(ii) Using Figure 1 and 2, compare the levels of the boat and the volumes of water
displaced by the boat.
………………………………………………………………………………………
………………………………………………………………………………………..
………………………………………………………………………………………..
………………………………………………………………………………………..
………………………………………………………………………………………..
Relating the mass of the boat with its load, the volume of water displaced and the
density of the water, deduce a relevant physics concept.
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………………………
(iii) Name the physics principle that explains the above situation.
…………………………………………………………………………………………….
b) A submarine can sail on the sea surface and under the sea. Explain how a submarine on the
surface submerges.
21.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
321
(3 marks)
c) Figures 3.5(c) and 3.5(d) below illustrate the working principle of a hydrometer.
The depth to which the test tube sinks depends on its surrounding liquid.
Draw a diagram that shows the design of your hydrometer and in your explanation, emphasis
the following aspects:
(i) the stability of the hydrometer
(ii) the sensitivity of the hydrometer
(iii) the ability to measure a wide range of densities of liquids
(iv) the calibration of the hydrometer. [10m]
22.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
322
B E R N O U L L I ’ S P R I N C I P L E
Definition
AEROFOIL
In a steady flow of fluid, the _ pressure __in the fluid is _decreases__ when the velocity
of the fluid is high and vice versa.
Figure below shows an __ aerofoil__ The upper region of the aerofoil has _ higher _ air
velocity than the lower region of the aerofoil.
By Bernoulli’s principle, the lower region has __higher ___ pressure than the upper
region of the aerofoil. This causes a __lifting force act____ on the aerofoil.
Situation
that
involved
with
Bernoulli’s
Principle
1.
Reminder :
1. Bernoulli’s Principle is obeyed only for moving fluid .
2. Fluid will move from high pressure into the low pressure.
Water flows through a uniform tube
from _ higher __ pressure to a __lower __
pressure area. Fluid pressure decreases
linearly;
PA > PB > PC
VA < VB < VC
Therefore hA > hB > hC
3.6
23.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
323
2. Venturi tube
3.
4.
Exercise
1. If the height of the fluid in tube L is h1,
and that is tube M is h2, which of the
following is true?
A. h1 > h2 because v1 > v2
B. h1 < h2 because v1 < v2
C. h1 > h2 because v1 < v2
D. h1 < h2 because v1 > v2
2. Aeroplane wingsact as aerofoils. What is the
funtion of an aerofoil?
A. To raise up the aeroplane.
B. To increase the speed of air flow at the surface
of wing.
C. To reduce the air resistance and the drag force.
Water flows through a non uniform tube,
the velocity of the fluid;
VB > VC > V A
VC is the highest because water is forces to
flow through a constriction at A, hence it
speed up.
Pressure of fluid;
PA > PC > PB
Therefore; hA > hC > hB
When the air is not flowing the pressure is
same at every point. When the air is
allowed to flow in, the velocity of the fluid;
VB > VC > V A
Because the crosssectional area at B is the
smallest.
Pressure of fluid;
PA > PC > PB
Therefore; hB > hC > hA
Water flows around the ping pong ball at _ high__ speed
through the filter.
Higher atmospheric pressure produces a __ upward force_
which is larger than __downward force __ of ping pong
ball.
Ping pong ball is pushed __ upward __ by upward force
and does not drop.
24.
Physics Module Form 4 Chapter 3 – Forces & Pressure GCKL 2011
324
3. Which of the following instruments is not
based on Bernoulli’s principle?
A. Bunsen burner
B. Car carburettor
C. Hydraullic jack
D. Flight of an airplane
4. Which of the following relates two quantities in
Bernoulli’s principle?
A. Velocity and force
B. Pressure and momentum
C. Velocity and pressure
D. Force and momentum
5. A boy standing by the road side. When a big lorry passed in front of him, the boy feels a pull towards
the lorry. This phenomenon can be explained by
A. Pascal’s principle
B. Bernoulli’s principle
C. Archimedes’ principle
6. As a researcher in a boat manufacturing company. , you are assigned to study metal characteristics
used to make the boat.
You are given four choices of metals P, Q, R and S. The table below shows
the characteristics for the four metals.
Metal Shape Density
Kgm 3
Specific Heat
Capacity
Strength
P Streamlined 900 Low High
Q Oval 452 High High
R Circle 387 Low High
S Streamlined 500 High High
Table 1
Based on table 1
i) Explain the suitable characteristics of the metal to be used as the material to make the boat.
( 8 marks)
ii) Determine the most suitable metal to be used as the material to make the boat and give your
reasons. ( 2 marks)
Clipping is a handy way to collect and organize the most important slides from a presentation. You can keep your great finds in clipboards organized around topics.
Be the first to comment