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

Question # 1

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 # 2

Define center of mass and explain it with the help of example

Ans 1: Centre of mas: center of mass of a system is a point where an applied force causes the system to move without rotationExplanation: it is observed that the center of mass of system moves as if its entire mass is confined at that points, the force acting on this point will not produce torque.

Question # 3

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 # 4

Explain principle of moments

Ans 1: Principle of moment: a body is balanced if the sum o clockwise moments acting on the body is equal to the sum of anticlockwise moments acting on it.There are two types of momentsClockwise moment, anticlockwise moment
Ans 2: Clockwise moment: 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
Ans 3: Anticlockwise moment: a force that turns a spanner in the anticlockwise direction generally used to loosen a nut. The torque or moment of force so produced is called anticlockwise moment.

Question # 5

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 # 6

Discuss briefly addition of forces

Ans 1: Addition of forces: force is a vector quantity. it has both magitude and direction; therre fore , forces are not added b ordinary arithmetical rules. when forces are added, we get a resultant force.
Ans 2: Resultant force: a resultant force is a single force that has the same effect as the combined effect of all the forces to be added
Ans 3: Head to tail rule; a graphical method used to fin resultatnt of two or more forces is called head to tail rule

Question # 7

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 # 8

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 # 9

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 # 10

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

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

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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 (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.

Define center of mass and explain it with the help of example

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.

Explain principle of moments

Write and explain the states of equilibrium

Discuss briefly addition of forces

State and explain mathematically first condition for equilibrium

How position of center of mass effects stability

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

state and explain second condition for equilibrium.

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 (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.

Define center of mass and explain it with the help of example

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.

Explain principle of moments

Write and explain the states of equilibrium

Discuss briefly addition of forces

State and explain mathematically first condition for equilibrium

How position of center of mass effects stability

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

state and explain second condition for equilibrium.

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

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