Matric Part 1/9th Class Physics Chapter 4 Long Question With Answer for Unit 4 Turning Effect of Forces

Question # 1

Q no: 7(A) Define parallel forces. Also explain its types or what is the difference between Like and Unlike parallel forces?

Ans 1: We often come accrossobjects on which many forces are acting.
In many cases, we find all or some of the forces acting on a body in the same of the forces actinf on a body in the same direction for example, many people push a bus it in the. Why all of them push it in the same direction? All these forces are applied in the same direction so these are all parallel to each other. Such forces which are parallel to each other are called parallel forces
Types:
There are two types of parallel forces
1- Like parallel force
2- Unlike parallel force

1- Like parallel forces:
Like parallel forces are those forces that are parallel to each other and have the same direction

2- Unlike Parallel forces:
Unlike parallel forces are the forces that are parallel but have directions opposite to each other.

Question # 2

A mechanic tightens the nut of a bicycle using a 15 cm long spannerby exerting a force of 200 N. Find the torque has tightened it.

Ans 1: Solutions:
F= 200N
L= 15cm = 0.15m
t= ?
t= F x L
t = 200 x 0.15
t =30Nm Ans

Question # 3

Write and explain the states of equilibrium

Ans 1: States of equilibrium: there are three states of equilibriumStable equilibrium ,Unstable equilibrium, Neutral equilibrium
Ans 2: Stable equilibrium: a body is said to be in stable equilibrium if after a slight tilt it returns to its previous positionExplanation: when a body is in stable equilibrium its center of gravity is at the lowest position. When it is tilted, its center of gravity rises. It returns to its state of sable equilibrium by lowering its center of gravity. Note that a body remains in state o stable equilibrium as long as the center of gravity acts through the base of the bodyExample: consider a block. when the block is tilt its entre of gravity G rises passes through its base in the tilt position. the block returns to its previous position. If the vertical line through G gets out of its base . the block does not return to its previous position. That is why a vehicle is made heavy at its bottom to keep its center of gravity as low as possible. A low center of gravity keep it stable. Moreover , the base of a vehicle is made wide so that the vertical line passing through its center of gravity should not get out of its base during a turn
Ans 3: Unstable equilibrium; if a body does not return to its previous position when et free after slightest till is said to b in unstable equilibriumExplanation: in state of unstable equilibrium C.G is at is highest position. Try to keep a pencil in vertical position on its top. whenever we leave it the pencil will topple over its top and hence fall down. Because of its center of gravity becomes lower and its weight acts out of its base. So the pencil is in the unstable equilibrium
Ans 4: Neutral equilibrium: if a body remains in its new position when disturbed from its previous position, it is said to be in state of neutral equilibriumExplanation: in neutral equilibrium C.G of the body remains at the same height . When a ball is placed on a horizontal surface and after displacing it the ball attains a new position and does not return but in both the positions its center of gravity remains at the same level . So a ball on a horizontal surface is in neutral equilibrium.

Question # 4

Explain like parallel and unlike parallel forces

Ans 1: Parallel forces: such forces which are parallel to each other are called parallel forces.ORthe forces which can never cross 3each other a re called parallel forces.Example: we often come across objects on which many forces are acting in many cases, we find some or all forces acting on the body in the same direction e.g. many people push a bus to start it, all the people apply the forces in the same direction so thy are called parallel forces.
Ans 2: Like parallel force: like parallel forces are the forces that are parallel to each other and have same directionExample: consider a bag with apples in it. The weight of the bag is due to the weight of all apples in it. Since the weight of every apple in the bag is the force of gravity acting on it vertically down words, therefore weight of all apples are parallel forces
Ans 3: Unlike parallel forces: unlike parallel forces are the forces that are parallel but have directions opposite to each otherExample: an apple is suspended by a string: The string is stretched due to its weight. The forces acting on it are weight of the apple acting down words, and tension in the string pulling it vertically upwards . The two forces are parallel but opposite to each other . These force are called unlike parallel forces

Question # 5

Q no: 7 (B) A force is acting on a body making an angle of 30 with the horizontal. The horizontal component of the forceis 20 N. Find the force.

Ans 1: Solution:
=20 N
Q = 30°
F = ?
As we know that
Fx= F cosθ
F = Fx/Cosθ
F = 20/cos30°
F = 20//o.866
F = 23.09N
F= 23.1 N

Question # 6

How position of center of mass effects stability

Ans 1: center of mass helps in stability. T make the object stable, center of mass is kept as low as possibleExample: Racing cars are made heavy at the bottom and height is kept as low as possible.Circular artist such as tight rope walker use long poles to lower their center of mass.In above two examples low center of mass helps them to prevent from topple over

Question # 7

Q no:6(B) The steering of a has a radius 16 cm. Find the torque produced by a couple of 50 N.

Ans 1:
F = 50 N
r= 16 cm
d= AB = 32cm =0.32m
t=?
As we know that
t = Fx AB
t = 50 x 0.32
t = 16Nm

Question # 8

State and explain mathematically first condition for equilibrium

Ans 1: First condition of equilibrium: a body is said to satisfy first condition of equilibrium if the resultant of all the forces acting on it zeroForces can act in two waysHorizontally, Vertically
Ans 2: Forces acting on x-axisExample: in rope pulling two teams, pull the rope in opposite direction. If both forces are equal then rope is in state of equilibrium and satisfyingly the first condition
Ans 3: Force acting on y-axis: resultant force can act on y-axis ( vertical direction0. If sum of two forces is zero the body is equilibriumExample; consider a bulb hanging with a wire is in equilibrium because weight of bulb and the tension in wire are equal in magnitude and opposite in direction and cancel their effect and satisfying the first condition of equilibrium
Ans 4: Result; hence, a body is in equilibrium if resultant of all forces is zero.

Question # 9

state and explain second condition for equilibrium.

Ans 1: Second condition for equilibrium: if the sum of all the torques acting on a body is zero then the body is in state of equilibrium
Ans 2: Explanation: consider a body pulled by the forces F1 and F2. The two forces are equal but opposite to each other . Both are acting along the same line, hence their resultant will be zero. According to first condition the body will be in equilibrium
Ans 3: NoteClockwise rotation: clockwise rotation is taken as negativeAnticlockwise rotation: anticlockwise rotation is taken as positive

Question # 10

Q no :6(a) What is meant by principle of moments? Explain clockwise torque and anticlockwise torque.

Ans 1: Principle of Moments:
A body is balanced if the sum of clockwise moments acting on the body is equal to the sum of anticlockwise moments acting on it
Explanation:
A force that turns a spanner in the clockwise direction is generally used to tighten a nut. The torque or moment of the force so produced is called Clockwise moment. On the other hand to loosen a nut, the force is applied such that it turns the nut , the force is applied such that it turns the nut, the force is applied such that it turns the nut in the anticlockwise direction. The torque or moment of the force so produced is called anticlockwise direction. The torque or moment of the force so produced is called anticlockwise moment.

Latest Educational News Stories

Pakistan's Largest Database of Colleges and Universities

BS Programs

University Past Papers

University Results

Exam Results 2024

Study Abroad Programs and Opportunities for Pakistani Students

Matric Part 1/9th Class Physics Chapter 4 Long Question With Answer for Unit 4 Turning Effect of Forces

9th Class English Medium Subjects

9th Class Urdu Medium Subjects

Online Long Questions For Chapter 4 "9th Class Physics Chapter 4 Long Question Preparation "

Physics (New Book) - 9th Class Physics Chapter 4 Long Question Preparation

Q no: 7(A) Define parallel forces. Also explain its types or what is the difference between Like and Unlike parallel forces?

A mechanic tightens the nut of a bicycle using a 15 cm long spannerby exerting a force of 200 N. Find the torque has tightened it.

Write and explain the states of equilibrium

Explain like parallel and unlike parallel forces

Q no: 7 (B) A force is acting on a body making an angle of 30 with the horizontal. The horizontal component of the forceis 20 N. Find the force.

How position of center of mass effects stability

Q no:6(B) The steering of a has a radius 16 cm. Find the torque produced by a couple of 50 N.

State and explain mathematically first condition for equilibrium

state and explain second condition for equilibrium.

Q no :6(a) What is meant by principle of moments? Explain clockwise torque and anticlockwise torque.

Prepare Complete Set Wise Questions For Chapter 4 "9th Class Physics Chapter 4 Long Question Preparation "

Set 1

9th Class Physics Chapter 4 Long Question Preparation - Set 1

Q no: 7(A) Define parallel forces. Also explain its types or what is the difference between Like and Unlike parallel forces?

A mechanic tightens the nut of a bicycle using a 15 cm long spannerby exerting a force of 200 N. Find the torque has tightened it.

Write and explain the states of equilibrium

Explain like parallel and unlike parallel forces

Q no: 7 (B) A force is acting on a body making an angle of 30 with the horizontal. The horizontal component of the forceis 20 N. Find the force.

How position of center of mass effects stability

Q no:6(B) The steering of a has a radius 16 cm. Find the torque produced by a couple of 50 N.

State and explain mathematically first condition for equilibrium

state and explain second condition for equilibrium.

Q no :6(a) What is meant by principle of moments? Explain clockwise torque and anticlockwise torque.

9th class Physics Chapter 4 Long Q's (English Medium)