Matric Part 1/9th Class Physics Chapter 7 Long Question With Answer for Unit 7 Properties of Matter

Question # 1

Define elasticity. explain deforming force, stress, strain and tensile strain.

Ans 1: Elasticity: the property of a body to restore its original shape and size as the deformation force ceases to act is called elasticity.
Ans 2: Deforming force; the applied force that changes shape , length or volume of a substance is called deforming force. In most of the case s, the body returns to its original size and shaper as soon as the deforming force is removed.
Ans 3: Stress: the force acting on a unit area at the surface of a body is called stress
Unit: the S.I unit of stress is newton per square meter(Nm^-2).
It is a scalper quantity
Ans 4: Strain: the ratio between change in object and original object is known as strain. When stress acts on a body, it may change its length , volume, or shape.
Unit: it has no unit due to ration between similar quantities.
Ans 5: Tensile strain: when stress produces a change in the length of an object then the strain is called tensile strain.
Unit: it has no unit as it is simply a ration between two similar quantities.

Question # 2

State and explain Archimedes principle. Also prove it

Ans 1: Archimedes principle: when a body is totally or partially immersed in a liquid, an upthrust acts on it equal to the weight of the liquid it displaces
Ans 2: Explanation: consider a solid cylinder of cross- sectional area A and height h increased in a liquid.
Let h1 and h2 be the depths of the top a nd bottom faces of cylinder respectively from surface of liquid.
Then,
h2-h1=h
If p1 and P2 are liquid pressures at depths h1 and h2 respectively and p is the density than according to equation which is given below
P=pgh
p1=pgh1
P2=pgh2
let the force F1 exerted at the cylinder top by liquid due to pressure P1 and F2 is exerted at the bottom of cylinder by liquid due to P2
So,
F1=P1A=pgh1
F2=P2A=pgh2
F1 and F2 are acting on opposite faces of the cylinder. Therefore the net force F will be (F2-F1) in the direction of F2
F2-F1=pgh2-pgh1
=pgA(h2-ha1)
h=h2-h1
F2-F1=pgv (v=Ah)
here Ah is the volume v of the cylinder and is equal to volume of liquid displaced by cylinder.
Ans 3: Upthrust fore; the upthrust force acting on the object is upward, when immersed in water is called an upthrust force . It acts on the body immersed in a liquid and is equal to the weight of liquid displaced

Question # 3

Explain breaking system in vehicles

Ans 1: Breaking system in vehicles: the braking system of cars, buses , etc. also work on Pascals law. The hydraulic breaks allow equal pressure to be transmitted throughout the liquid. When break pedal is pushed, it exerts a force on the master cylinder, which increases the liquid pressure in it. The liquid pressure is transmitted equally through the liquid in the metal pipes to all the pistons of other cylinder s. Due to the increase in liquid pressure, the piston in the cylinders move outward pressings the break pads with the brake drums. The force of friction between the brake pads and the brake drums stops the wheels.

Question # 4

State and explain Young's modulus.

Ans 1: Young' modulus; the ratio of stress to tensile strain is called young's modulus.
Ans 2: Explanation; consider a long bar of length l and cross sectional area A. Let an external force F equal to the weight stretches it such that the stretched length become L. According to Hook's law, the ratio of the stress to tensile strain is constant within the elastic limit of the body.

Question # 5

Q no:6 (A) State the Pascal's law. What are its applications in our daily life?

Ans 1: Pascal's Law:
Pressure applied at any point of liquid anclosedin a containeris transmitted without the loss to all other parts of the liquid.
An external force applied on the surface of a liquid increases the liquid pressure at the surface of the liquid. This increase in liquid pressure is transmitted equally to all direction and to the walls of the container in which it is filled.
Applications of Pascal's Law:
Hydraulic press is a machine which works on the principle which works on the principle of Pascal's law. It consists of two cylinders which are fitted with pistons of cross-sectional area a and A. The object is to be compressed is placed over the pistonof large cross- sectional areea A. The force is applied on the piston of cross-sectional area a.

The pressure P produced by small piston is transmitted through the liquid and acts on the large piston and a force F₂ acts on
A Which is much larger than F₁.

Question # 6

Define pressure. explain it with examples

Ans 1: Pressure; the force acting normally per unit area on the surface of a body is called pressure.
unit: its S.I unit is Nm-2 or pascal(Pa). Thus 1 Nm-2 =1Pa
Dependence; it depends upon area and applied force
Ans 2: Examples;
1. press a pencil from its ends between the palms. The palm pressing the tip feels much more pain than the palm pressing its blunt end.
2. we can push a drawing pin into a wooden board by pressing it by out thumb. It is because the force we apply on the drawing pin is confined just at a very small area under its sharp tip. A drawing pin with a blunt tip would be very difficult to push into the board due to the large area of its tip.

Question # 7

State and explain Hook's law

Ans 1: Hook's law: the strain produced in a body by the stress applied to it is directly proportional to the stress with in the elastic limit of the body
Ans 2: Explanation; Hook's law is applicable to all kinds of deformation and all type of matter i.e. solids, liquids or gases within certain limit. This limit tells the maximum stress that can be safely applied on a body with out causing permanent deformation in its length volume or shape.
In other words, it is a limit with in which a body recovers its original length, volume or shape after the deforming force is removed. When a stress crosses this limit, called the elastic limit, a body is permanently deformed and is unable to restore its original state after the stress is removed

Question # 8

Q no 6B) Thedensity of air is 1.3 Find the mass of air in measuring 8m x 5m x 4m.

Ans 1: Data:
= 1.3
v= 8m x 5m x 4m
= 160m³
m = ?
Solution:
As we know that
Density = Mass/Volume
Mass = Density x Volume
=1.3 x 160
m = 208kg Ans

Question # 9

What is density? explain

Ans 1: Density; density of a substance is defined as its mass per unit volume
Unit: its S.I unit is kilogram per cubic meter (kgm^-3)
Ans 2: Explanation; if we take equal volume of iron and wood, then we can easily declare that iron is heavier than wood. it means that density of iron is heavier than wood

Question # 10

Q no: 5 (A) Derive the formula of Young Modulus.?

Ans 1: Young's Modulus:
The ratio of stress and strain is a constant within the elastic limit , this constant is called the young's Modulus.
Mathematical Form:
Consider a long bar of length L_o and cross- sectional area A let an external force F is equal to weight stretches it such that the stretched length becomes L.
Mathematically.
Young's Modulus = Y = Stress/Tensile strain
Let ▲L =L-L_o
Since-
Stress = Force/Area =F/A
And
Tensile strain = L-L_o/L_o= ▲L/L_o
As
Young's modulus = Y = Stress/Tensile strain
=F/A x L_o/▲L
= F x L_o/A x▲L

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Matric Part 1/9th Class Physics Chapter 7 Long Question With Answer for Unit 7 Properties of Matter

9th Class English Medium Subjects

9th Class Urdu Medium Subjects

Online Long Questions For Chapter 7 "9th Class Physics Chapter 7 Long Question Preparation "

Physics (New Book) - 9th Class Physics Chapter 7 Long Question Preparation

Define elasticity. explain deforming force, stress, strain and tensile strain.

State and explain Archimedes principle. Also prove it

Explain breaking system in vehicles

State and explain Young's modulus.

Q no:6 (A) State the Pascal's law. What are its applications in our daily life?

Define pressure. explain it with examples

State and explain Hook's law

Q no 6B) Thedensity of air is 1.3 Find the mass of air in measuring 8m x 5m x 4m.

What is density? explain

Q no: 5 (A) Derive the formula of Young Modulus.?

Prepare Complete Set Wise Questions For Chapter 7 "9th Class Physics Chapter 7 Long Question Preparation "

Set 1

Set 2

9th Class Physics Chapter 7 Long Question Preparation - Set 1

Define elasticity. explain deforming force, stress, strain and tensile strain.

State and explain Archimedes principle. Also prove it

Explain breaking system in vehicles

State and explain Young's modulus.

Q no:6 (A) State the Pascal's law. What are its applications in our daily life?

Define pressure. explain it with examples

State and explain Hook's law

Q no 6B) Thedensity of air is 1.3 Find the mass of air in measuring 8m x 5m x 4m.

What is density? explain

Q no: 5 (A) Derive the formula of Young Modulus.?

9th Class Physics Chapter 7 Long Question Preparation - Set 2

Q no 6B) Thedensity of air is 1.3 Find the mass of air in measuring 8m x 5m x 4m.

Q no:6 (A) State the Pascal's law. What are its applications in our daily life?

What is density? explain

Define atmospheric pressure . explain it

Define elasticity. explain deforming force, stress, strain and tensile strain.

Explain how submarine moves up the water surface down into water

Define pressure. explain it with examples

What is the principle of floatation. explain

State and explain Pascals law

How we can find the density of an object

9th class Physics Chapter 7 Long Q's (English Medium)

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