Define pressure. Give its SI unit.
The total force applied per unit area is called pressure.
Pressure (P) = Force (F) / Area (A)
Its SI unit is pascal (Pa).
Let us consider a hydraulic machine of 2 vessels of CSA 'A1' and 'A2' respectively. These vessels are fitted with watertight frictionless pistons. The CSA of the small vessel is 'A1' and large vessel is 'A2'. So, 'A1' < 'A2'.
When a force 'F1' is applied on the small piston of area 'A1', a pressure 'P1' is exerted on the small piston. According to Pascal's law:
Pressure in small piston = Pressure in the large piston
i. e. P1 = P2
or, F1 / A1 = F2 / A2
or, F1.A2 = F2.A1
Since A2 > A1,F1 >...
Let us consider a cylinder of height 'h' and uniform CSA 'A' is immersed in a liquid of density 'd'. If h1 and h2 are the depths of the upper and lower surface of the immersed cylinder then,
Force on the upper surface, F1 = P1 . A = h1dgA
Force on the lower surface, F2 = P2 . A = h2dgA
Here, g is the acceleration due to gravity.
Now, upthrust (U) = F2 - F1
= h2dgA - h1dgA
= (h2 - h1)dgA
= hdgA Since h2 - h1 = h
= Vdg Since Ah = V
A is water and B is air out of three media because in the water there is medium weight due to the medium upthrust exerted by water whereas in the air there is maximum weight because of the least upthrust exerted by air.
In air media, 10 N = 1 kg
So, 28 N = 28 / 10 = 2.8 kg
Therefore, the mass of stone is 2.8 kg.
As we all know that,P = F/Aso, P1/A
Usually, the bags are made to carry heavy loads. The handles should be able to handle the pressure exerted by the loads. Otherwise, the handles will break. So, to reduce the exerted pressure, and handle the bag easily, the handles of the bag are made broader to increase its area.
As we all know that,P = F/Aso, P1/A
We also know that rails are heavy vehicles with tons of loads. So, it exerts high pressure on its tracks while traveling and has chances to sink. Hence, to prevent sinking by reducing the pressure exerted by rail, the railway tracks are laid on large sleepers increasing its area.
As we all know that, P = F/A so, P1/A
In the graveled roads, there are many sharp-edged stones on the surface. While walking on it, more pressure is exerted by the sharp stones (due to less area) and it causes pain and difficulties while walking on the graveled roads.
We have, P = F/A so, P1/A
Usually, nails need more pressure to be inserted for different purposes in woods and metals. If it has a pointed end, the area of the edge is less and more pressure can be exerted with less force. So, it will be easy to work with nails. Hence, nails are made to have a pointed end.
We all know thatupthrust = Vdg so, upthrustd
The density of the concentrated salt solution is higher than that of pure water. So, more upthrust is exerted by the salt solution than by pure water. Hence, the egg floats in it but not in pure water.
We know that upthrust exerted by water is always greater than air. So, the bucket of water is uplifted by greater upthrust of water in water but the upthrust of air isn't much effective. So, it is easier to lift the bucket of water until it remains inside the water.
According to the law of floatation, a body floats on a liquid if it can displace the liquid equal to its weight. The body can displace the liquid equal to its volume. The volume of nails is less. So, it displaces less water and sinks. However, the ship displaces a large amount of water and floats due to the influence of high upthrust. Hence, an iron nail sinks in water but the ship made of iron floats.
We know that seawater is found as saline water (salt solution). So, seawater has a higher density than river water. Also, upthrustdensity. So, more upthrust is exerted in seawater than in river water. Hence, it is easier to swim in seawater than in river water.
The pressure exerted by the atmosphere due to its weight is called atmospheric pressure.Its importance is:
A syringe is a simple pump consisting of a plunger or piston that fits tightly in a tube that can take in and expel a liquid or gas. Its uses are as listed below:
The syringe is made up of a plastic piston and barrel. The piston is fitted tightly in the barrel from the open end. The other end that is closed leaving a small tube to pass out is called a nozzle. When the piston or plunger is pulled, the vacuum is created inside the barrel and the air or liquid flows in through the nozzle. And when the piston is pushed in, the liquid or air inside flows out.
A water pump is a manually operated pump that uses human power to lift the underground water to the surface.
A water pump consists of two valves V1 and V2. Valve V1 moves up and down along with the piston and valve V2 is connected to the base of the barrel. Similarly, the barrel is connected to a pipe and the pipe is inserted into the ground. When the handle is pushed down, the piston moves upward, which creates vacuum valves between V1 and V2. In this state, V1 closes, and water enters the...
i. Force and pressure
|It is the product of mass and acceleration.||It is the total force applied per unit area.|
|Force = m.a||Pressure = F/A|
|Its SI unit is Newton (N).||Its SI unit is Pascal (Pa).|
ii. Archimede's principle and the law of flotation.
| Archimede's principle || Law of flotation |
|It states that when a body is partially or totally immersed in a liquid, it experiences the upthrust equal to the weight of the liquid displaced by it.||It states that a body floats on...|
The weight of water displaced by the ship will be more than its own weight i.e., 5*105because it is built in such a way that the weight of the water displaced by the ship is more than its weight itself. So that it will not sink in seawater
Most hand pumps used to inflate bike tires are reciprocating pumps. They have a piston inside and two one-way valves: one going to the bike tire and one to the outside air. When the pump is pulled up, the pressure inside decreases. This pulls in air from the outside but closes the valve to the bike tire. When the piston is pushed down again, it compresses the air inside. This closes the inlet valve and opens the valve to the tire, pushing air into the bike.
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