# Pressure Force and Area Relationship

Many people do not know the pressure, force, and area relationship. pressure is inversely proportional to the area and directly proportional to force.

Here is an assessment of pressure, force and area relationship and kinds of pressure.

First Assessment Quiz with 20 MCQs

### Question Text

See other assessments of science grade 8

Note: See notes of this chapter at the end of this assessment

## What is pressure?

The force acting normally on the unit area is called pressure.

Define force.

Ans: The force is an agent that stops or moves the body, or tries to stop or move the body. Its unit is Newton. It is denoted by ‘N’.

Define area.

Ans: Area is defined as the number of square units that covers a closed figure. Its unit is m2.

Define pressure.

Ans:  The force acting normally on the unit area is called pressure.

What is the unit of area?

Ans:  The unit of area is a square meter. It is denoted by m2.

What is the unit of force?

Ans:  The unit of force is Newton. It is denoted by N.

What is the unit of pressure? Define SI unit of pressure.

Ans: The unit of pressure is Pascal. It is denoted by Pa.

When a force of one Newton acts normally on an area of one square meter, the pressure on this area will be one Pa.

Give commonly used units of force.

Ans: Newton is a unit of force.

Give the commonly used units of area.

Ans: “m2” is commonly used as the unit of area.

Give the commonly used units of pressure.

Ans: N/m2 and Pascal have commonly used units of pressure.

What is the relation between pressure, force and area?

Ans: If the pressure is denoted by P, force is denoted by F and area is denoted by A, then

P = F/A • Pressure is directly proportional to force and inversely proportional to area.
• If the same force is applied to different areas, the smaller area will feel high pressure while the larger area will feel low pressure.
• If different forces act on the same area, the larger force will exert high pressure while the smaller force will exert low pressure.

### What is the relationship between pressure force and area?

Explain water pressure.

Ans: The force exerted by the molecules of water on the unit area of the walls of a container is called water pressure.

What are the properties of water pressure?

Ans:i. The water pressure in a vessel increases with the increase in depth.

The water pressure acts perpendicularly to the walls of the vessels.

Why the supporting walls of a dam are built very broad at the bottom?

Ans: Since the water pressure increases with the increase in depth, therefore walls of dam are built very broad at the bottom.

Why do divers feel an increase in pressure on their eardrums in depths of a few meters only?

Ans: The water pressure increases by 10,000 Pa for every meter down in the sea.

That is why the sea divers feel an increase in pressure on their eardrums even a few meters below the surface of the water.

What is hydrostatic pressure?

Ans: The pressure which increases with the depth of the liquid in the container is called hydrostatic pressure.

State Pascal’s law.

Ans: Pascal’s law states that fluids enclosed in a vessel exert pressure that is transmitted equally in all directions.

## Define hydraulics.

Ans:  The branch of science that deals with the transmission of fluid pressure through pipes as a source of mechanical force is called hydraulics. It is used to produce large force with the help of small force.

Describe an application of Pascal’s law.

Ans: Hydraulic system or jack system is an example of Pascal’s law. In this system, a small force is applied on a small piston, which produces pressure on the liquid in pipes. This pressure is transmitted through a pipe to a very large cylinder, fitted with a large piston. Since the area of this piston is bigger, so a very large force is produced by pressure. This force of pressure is used to lift heavy objects like a car.

The pressure brake system also works like a jack system. When a driver presses the brake pedal, this force is transmitted to the wheel disk without loss of force, and force of friction is produced to stop the wheel.

Define pneumatics.

Ans: The branch of science with deals with the study and applications of pressurized gas to produce mechanical motion is called pneumatics.

Air brake systems, spray guns and aerosols are examples of pneumatics.

Describe the use of the pneumatic system in daily life.

Ans: Compressed air is used in the tyres of vehicles for smooth running.

This system is used for spraying paints.  Compressed air is used in the air brake system.

Explain atmospheric pressure.

Ans: The weight of the air column per unit area on a surface is called atmospheric pressure. Its unit is a standard atmosphere and it is abbreviated as ‘atm’.

What do you mean by ‘atm’?

Ans: ‘atm’ is the short form of standard atmosphere. It is a unit of atmospheric pressure. One atmosphere (1 atm) is equal to 101,300 Pa or 101.3 KPa.

How atmospheric pressure is measured?

Ans: Atmospheric pressure is measured by an instrument named a barometer.

How much atmospheric pressure is around us?

Ans: The atmospheric pressure around us at ground level is 100,000 Pa.  Or  (1000 KPa).

What is a pressure altimeter? And where it is used?

Ans: When a barometer is calibrated to indicate altitude, this instrument is called a pressure altimeter. Skydivers and mountain climbers use it. it is also used in air crafts.

Differentiate between hydrostatic pressure and atmospheric pressure.

Ans: Hydrostatic Pressure: The pressure which increases with the depth of the liquid in the container is called hydrostatic pressure.

Atmospheric Pressure: The weight of the air column per unit area on a surface is called atmospheric pressure.

How does atmospheric pressure vary with the altitude?

Ans: As we go up in the air, atmospheric pressure decreases.

What is the unit of pressure?

What is the unit of force?

What is the unit of area?

What is pressure?

Why are the supporting walls of dams are built very broad at the bottom?

What is hydrostatic pressure?

What are the properties of hydrostatic pressure?

How do you define hydraulics?

How does the jack system work?

What are the properties of liquid pressure in a closed container?