Extra Calculation Questions - Pressure

PRESSURE
1.       What pressure does a diver experiences at a depth of 16 m in a diving tank? The density of water is 1,000 Kg/m3 and the atmospheric pressure is 100,000 Pa
2.       The figure below shows a simple type of   hydraulic braking system. The areas of cross section of the small cylinder and large cylinder are 0.0004 m2 and 0.0024 m2 respectively. A pedal is pushed against the piston in the small cylinder with a force of 90 N.
i)        Calculate the pressure exerted on the brake fluid.
ii)       Calculate the force exerted by the brake fluid on the piston of the large cylinder.
3.       In a hydraulic pressure system, a force of 25 N is applied to a piston of area o.50 m2. The area of the other piston is 1.5 m2. Calculate the pressure transmitted through the system and the force exerted on the other piston
4.       What is the pressure exerted on the ground by the block of weight 20 N if the area in contact with the ground is 0.008 m2?
5.       Find the pressure exerted by a force of 80 newtons on an area of 25 cm².Give your answer in newtons/m²
6.       The cuboid and the cube below are placed on the floor.
The cuboid has a weight of 60 N
The cube has a weight of 40 N
Which exerts a greater pressure on the ground? You must show your working.

7.       A television is placed on a table. The area of the television in contact with the table is 750 cm². The pressure on the table is 1760 newtons/m². Work out the force exerted by the television on the table.
8.       Calculate the pressure under a woman's feet if her mass is 50 kg and the area of her shoes in contact with the ground is
i)        2.00 cm2 (high heel)
ii)       200 cm2 (flat sole)
(Take acceleration due to gravity, g = 10 ms-2)
9.       Calculate the pressure 10,000 cm below the surface of water. Density of water is 1 g/cm3.
(Take the weight of 1 kg mass to be 10 N).
10.   A block weighing 100,000 g rests on an area of 40,000 m2. Calculate the pressure exerted by the block on the surface which supports it.
11.   A block of metal of dimensions 0.5 m x 0.6 m x 1.0 m has a mass of 300 kg. Calculate the maximum and minimum pressure acting on the ground
12.   A student pressing a thumbtack into a piece of wood with a force of 20 N.  The surface area of the head of the thumbtack is 1 cmand the cross-sectional area of the tip of the thumbtack is 0.01 cm2
Calculate:
a)       the pressure exerted by the student’s thumb on the head of the thumbtack 
b)        the pressure of the tip of the thumbtack on the wood.
c)       What conclusion can be drawn from your answers to (a) and (b)?
13.   If the density of sea water is 1.150 gcm-3, calculate the pressure below 40 m of sea water due to the water alone. 
14.   The figure shows a cylinder containing liquid mercury.  
  
What is the pressure caused by the liquid mercury at the point P?
[Density of liquid mercury is 1.36 x 105 kgm-3]

15.  The figure shows a basic hydraulic system has small and large pistons with cross-sectional area of 0.005 m2 and 0.1 m2 respectively. A force of 20 N is applied to the small piston.
Determine 
a)       The pressure transmitted in the hydraulic fluid.
b)      The mass of the load.
16.   A fisherman with a mass of 75 Kg falls asleep on his four-legged chair of mass 5 Kg. If each leg of the chair has a surface area of 2.5 x 10-4 m2 in contact with the ground, what is the average pressure exerted by the fisherman and the chair on the ground?
17.   A scale which reads 0 in the vacuum of space is placed on the surface of planet Physica. On the planet’s surface, the scale indicates a force of 10,000 Newtons. Calculate the surface area of the scale, given that atmospheric pressure on the surface of Physica is 80,000 Pascal.
18.   A barber raises his customer’s chair by applying a force of 150 N to a hydraulic piston of area 0.01 m2. If the chair is attached to a piston of area 0.1 m2, how massive a customer can the chair raise? Assume the chair itself has a mass of 5 kg.
19.   A hydraulic system is used to lift a 2000-kg vehicle in an auto garage. If the vehicle sits on a piston of area 0.5 square meters, and a force is applied to a piston of area 0.03 square meters, what is the minimum force that must be applied to lift the vehicle?
20.   A hydraulic Press has a large circular piston of radius 0.8 m and a circular plunger of radius 0.1 m. A force of 200 N is exerted by the plunger.
i)        Find the force exerted on the piston.
ii)       State one reason why the weight of the load just raised by the piston is less than this force?
iii)     If the plunger is moved through a distance of 0.64 m in exerting its force, through what distance is the piston raised?
21.   A rectangular solid block iron has 1.0 m x 0.6 m x 0.5 m and rest on a horizontal flat surface. If the density of the iron is 8000 Kg/m3, calculate;
i)        Maximum pressure which the block can exert on the surface
ii)       Minimum pressure which the block can exert on the surface
(Assume acceleration due to gravity = 10m/s2)
22.   A mercury barometer reads 760 mmHg at the foot of a mountain 440 m high. What is the barometer reading at the top of the mountain, assuming the average value of the density of air is 1.2 Kg/m3 and for mercury 13200 Kg/m3?

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