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# Form 1 Physics Questions and Answers on Pressure

In this course, we are going to solve Form 1 physics questions on pressure. Answers are available in video format.

Lessons (**43**)

- 1.
Fig. 2 shows a liquid being siphoned from one beaker to another. Refer to this diagram.
Indicate on the diagram the direction of flow of the liquid.

1m 52s - 2.
Show that the force driving the liquid through the U-tube is proportional to the height, h.

4m 23s - 3.
State what would happen to the flow if the system in Fig. 2 were put in a vacuum.

1m 47s - 4.
Fig. 2 shows a U-tube containing two liquids L1 and L2 of densities 1.8g #cm^-3# and 1.8g #cm^-3# respectively in equilibrium. Given that h1 = 8 cm, determine the value of h2.

3m 55s - 5.
A small nail may pierce an inflated car tyre and remain there without pressure reduction in the tyre. Explain this observation.

2m 6s - 6.
The height of the mercury column in a barometer at a place is 64cm. what would be the height of a column of paraffin in barometer at the same place?
(Density of paraffin = 8.0 x #10^2# # kgm^-3#)

4m 17s - 7.
State one advantage of fitting wide tyres on a vehicle that moves on earth roads.

2m 7s - 8.
State the reason why it may not be possible to suck liquid into your mouth using drinking straw on the surface of the moon.

2m 12s - 9.
A hole of area 2.0#cm^2# at the bottom of a tank 2.0m deep is closed with a cork. Determine the force on the cork when the tank is filled with water. (Density of water is 1000#kgm^-3# and acceleration due to gravity is 10#ms^-2#)

3m 1s - 10.
The total weight of a car with passengers is 25, 000N. The area of contact of each of the four tyres with the ground is #0.025m^2#. Determine the minimum car tyre pressure.

1m 20s - 11.
The reading on a mercury barometer at a place is 700mm. what is the pressure at the place in #Nm^-2#? (Density of mercury is 1.36 x 104# kgm^-3#)

2m 7s - 12.
State Pascal’s principle of transmission of pressure in fluids.

0m 26s - 13.
Figure 3 shows the levels of two liquids A and B after some air has been sucked out of the tubes through the tap. Use this information and the figure to answer questions 16 and 17.
State the reason for the rise in the levels of the liquids when air is sucked from the tube.

1m 11s - 14.
Given that the density of liquid B is 1200 #kgm^-3#, determine the density of liquid A.

2m 10s - 15.
Figure 4 shows a conical flask 15cm high, filled with a liquid of density 1200#kgm^-3#. The atmospheric pressure of the surrounding is 8.4 x# 10^4# Pa.
Determine the pressure at the point marked X, at the bottom of the flask.

2m 54s - 16.
Figure 2 shows two cylinders containing a liquid and connected with a tight-fitting flexible tube. The cylinders are fitted with air-tight pistons A and B as shown.
When equal forces, F, are applied on the pistons as shown, it is observed that piston A moves up while B moves down. Explain this observation.

2m 2s - 17.
Some water in a tin can was boiled for sometime. The tin can was then sealed and cooled. After sometime it collapsed. Explain this observation.

1m 3s - 18.
When bicycle pump was sealed at the nozzle and the handle slowly pushed towards the nozzle, the pressure of the air inside increased. Explain this observation.

0m 37s - 19.
Figure 9 shows syringe full of water. It has two identical holes A and B drilled along its cylinder. The cylinder nozzle is closed.
State with a reason how the speeds of the jets of water
from A and B compare when the piston is pushed into the cylinder.

1m 49s - 20.
In an experiment to demonstrate atmospheric pressure, a plastic bottle is partially filled with hot water and the bottle is then tightly corked. After sometime, the bottle starts to get deformed.

1m 51s - 21.
(a) Figure 14 shows a lift pump. Explain why, when the piston is:
(i) Pulled upwards, valve A opens while valve B closes.
(ii) Pushed downwards, valve A closes while valve B opens.
(b) After several strokes, water rises above the piston as shown in Figure 15.
State how water is removed from the cylinder through the spout.
(c) A lift pump can lift water to a maximum height of 10m. Determine the

6m 12s - 22.
State two factors that determine the pressure at a point in a liquid.

0m 45s - 23.
A student wearing sharp pointed heeled shoes is likely to damage a soft wooden floor. Explain.

0m 42s - 24.
A balloon is filled with hydrogen gas and then released into the air. It is observed that as it rises higher into the air it expands. Explain why it expands.

0m 37s - 25.
(a) State Pascal’s principle of transmission of pressure in liquids.
(b) Figure 10 shows heights two immiscible liquids X and Y in a U-tube (drawn to scale)
(i) State with a reason which of the two liquids X and Y has a higher density.
(ii) Determine the value of h.
(iii) Given that the density of liquid Y is p, write down an expression for the density d of liquid X in terms of p.

6m 32s - 26.
Figure 1 shows a defective straw used to suck milk from a glass.
It was observed that upon sucking the straw, milk did
Not rise up the straw. Explain this observation.

0m 58s - 27.
A force of 100 N is applied to an area of #100mm^2# . Determine the pressure exerted on the area in #Nm^(–2)#.

1m 16s - 28.
A girl standing upright exerts a pressure of 13600 #Nm^(–2)# on the floor. Given that the total area of contact of shoes and the floor is #0.0368m^2# , determine:
(a) the mass of the girl.
(b) the pressure she would exert on the floor if she stood on one foot.

3m 2s - 29.
Trucks which carry heavy loads have many wheels. Explain.

0m 40s - 30.
A block of copper of density 8.9 g/#cm^3# measures 5 cm × 3 cm × 2 cm. Given that the force of gravity is 10#Nkg^(–1)# , determine:
(a) the maximum pressure.
(b) the minimum pressure that it can exert on a horizontal surface.

3m 28s - 31.
Calculate the amount of force that must be applied on a blade of length 4 cm and thickness of 0.1 mm to exert a pressure of 5000000 Pa.

1m 21s - 32.
Calculate the pressure due to water experienced by a diver working 15 m below the surface of the sea. (Take g = 10#Nkg^(–1)# and density of sea water = 1.03#gcm^(-3) ) #

1m 23s - 33.
An outlet of diameter 1 m is made 20 m below the surface of water in a dam. Determine the force with which the water spews out when it is fully opened due to water pressure (Take g = 10 #Nkg^(–1)# and density of water = 1#gcm^(-3)) #

2m 43s - 34.
Explain why water storage tanks in houses are erected as high as possible.

0m 24s - 35.
Describe a simple experiment to demonstrate that the pressure in a liquid increases with depth.

1m 20s - 36.
The figure below shows a simple hydraulic press used to compress a bale. The cross-section areas of A and B are 0.002 #m^2# and 0.30 #m^2# respectively.
Determine the:
(a) pressure exerted on the oil by the force applied at A.
(b) pressure exerted on B by the oil.
(c) force produced on B compressing the bale.

2m 48s - 37.
Explain why there is a big difference between heights of water and mercury column that can be supported by atmospheric pressure.

0m 32s - 38.
The barometric height at sea level is 76 cm of mercury while that at a point on a highland is 74 cm of mercury. Determine the altitude of the point. (Take g as 10 N/kg, the density of mercury as 13600 #kgcm^(-3)# and density of air is 1.25 #kgcm^(-3) )#

3m 51s - 39.
The figure below shows a rubber sucker. Explain why the sucker sticks on a clean flat surface.

1m 42s - 40.
A sucker stuck on a flat surface was pulled by means of a spring balance as shown in figure below.
When the sucker was just about to be pulled off the surface, the spring balance reading was 40 N. Given that the area of the sucker was 4.4 cm^2 , determine the air pressure in #Nm^-2#.

1m 41s - 41.
Explain what is meant by a barometric liquid. Give an example of one such liquid, stating its properties.

0m 40s - 42.
A student in a place where the mercury barometer reads 75 cm wanted to make an alcohol barometer. If alcohol has a density of 800 #kgcm^(-3)# . Find the minimum length of the tube that could be used.

2m 6s - 43.
Two liquids were sucked up in two identical tubes as shown in the figure below. Given that the liquid in beaker #B_2# is water (density 1#gcm^(-3))#, determine the density of liquid in beaker #B_1# .

2m 5s