Question

What is buoyancy and thrust . define pressure and its SI unit. Please today ia my exam!

Answer 1

Here's your answer!!

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Let us first understand,

what is Buoyancy?

You may often have seen that when u throw some objects into water some of them sink into water while some of them float.

Why this happens??

The floating and sinking of an object is based on the concept of buoyancy.

For example :- if we throw say stone into water it sinks but when we throw plastic into water it floats.
So,whenever we throw something into water it will either float or sink it depends on the upward force exerted by the water.

◆The water exert an upward force on water and that upwards force on that object is called Buoyancy.
Due to upthrust the body immersed in liquid appears to be light compared to its original weight.

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◆The force acting on the object perpendicular to the surface is called as Thrust.
It's SI unit is Newton and it is a vector quantity.

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◆The physical quantity that express the dependence of Thrust on a area is called Pressure.

It can also be defined as the Force per unit area .If a Force F is applied on a surface of area A then pressure can be calculated as :-
P=F/A

It's SI unit is Pascal or N/m^2.

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Hope it helps you!! :)

Answer 2

Buoyancy
Buoyancy (also known as the buoyant force) is the force exerted on an object that is wholly or partly immersed in a fluid.
•The symbol for the magnitude of buoyancy is B or FB
•As a vector it must be stated with both magnitude and direction.
•Buoyancy acts upward for the kind of situations encountered in everyday experience.
|•| The SI unit of buoyancy is the newton [N].
•Buoyancy is caused by differences in pressure acting on opposite sides of an object immersed in a static fluid.

A typical situation:
1. The pressure on the bottom of an object is greater than the top
(since pressure increases with depth).
2. The force on the bottom pushes up and the force on the top pushes down
(since force is normal to the surface).
3. The direction of the net force due to the fluid is upward.



Thrust
Thrust is a force or a push. When a system pushes or accelerates mass in one direction, there is a thrust (force) just as large in the opposite direction.
•In math and physics, this is described by Isaac Newton ’s second and third laws . •Thrust is used to describe how strongly an engine pushes.
•It can be used for many kinds of vehicles and engines such as rockets, airplanes, plane (propeller) engines, and jet engines.
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Thrust is measured in “pounds of thrust” in the U.S. and in Newtons in the metric system. 4.45 Newtons of thrust equals 1 pound of thrust.
A pound of thrust is how much thrust it would take to keep a one pound object unmoving against the force of gravity on earth.


Pressure
Pressure is defined as force per unit area.
•It is usually more convenient to use pressure rather than force to describe the influences upon fluid behavior.
•For an object sitting on a surface, the force pressing on the surface is the
weight of the object, but in different orientations it might have a different area in contact with the surface and therefore exert a different pressure.
|•| The unit of pressure in the SI system is the pascal(Pa), defined as a force of one Newton per square meter.



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