Goyal Brothers Prakashan solutions for अ न्यू अप्रोच टू आईसीएसई [इंग्रजी] इयत्ता १० chapter 1 - Forces: Turning Forces and Uniform Circular Motion [Latest edition]

Define rigid body and support your answer by a practical example.

By drawing diagram define or explain:

1. Point of action of force.
2. Line of action of force.
3. Principle of transmissibility of force.

What do you understand by the term moment of force?

State the mathematical expression for moment of force.

Its moment of a force scalar or a vector quantity?

State the unit of moment of force in C.G.S. system.

State the S.I. unit of moment of force.

State when the moment of force is positive and when it is negative.

What force will produce a moment of force of 9 Nm of the perpendicular distance between the point of action of force and turning point is 40 cm?

Why are spanners with long handles easier to open nuts of a truck wheel as compared to spanners with short handles?

Why is it easier to tear a branch of tree by pulling it from its far end, rather than close to the trunk of tree?

Why is digging of a field is more easier with a spade of long handle than a spade with short handle?

Why is it easier to draw water from a hand pump with long handle as compared to pump with short handle?

A jack screw is provided with a long arm. Explain why?

Why is it easier to open a door by applying the force at the free end of it?

Explain the following:

A small boy balances a grown up man on see-saw.

The hand flour grinder is provided with a handle near the rim.

Diagram alongside shows a heavy roller with its axle at point O. It is to be pulled on the pavement XY by applying minimum possible force. Copy the diagram and mark on it the point P and the direction in which the minimum possible force is applied.

What is meant by equilibrium?

What do you mean by static equilibrium? Give one example.

What do you mean by dynamic equilibrium? Give one example.

A labourer is pushing a heavy stone with maximum force, but is unable to move it.

1. What is kind of equilibrium shown by the stone?
2. Name two sets of opposing forces acting on the stone.
3. Are the forces mentioned by you in equilibrium?

An aeroplane is flying high in sky at a constant speed.

1. What kind of equilibrium is shown by the aeroplane?
2. Name two sets of opposing forces acting on the aeroplane.
3. Are forces mentioned by you in equilibrium?

Define couple. 

Define the following:

Arm of couple

Define the moment of a couple.

State the mathematical expression of couple.

When a couple is (i) positive (ii) negative?

State absolute unit of couples in S.I. system.

Give two examples of a couple's actions in our daily life.

1. Mass of a body is 10³ kgf. Is this statement true?
2. If the answer in above question is No, then give a reason.
3. What is the mass of body?

Define centre of gravity.

State position of centre of gravity in the following bodies.

A square lamina

What is the position of the centre of gravity of a rectangular lamina?

At which point is the centre of gravity situated in a triangular lamina?

At which point is the centre of gravity situated in a circular lamina?

What is the position of the centre of gravity of a cylinder?

State position of centre of gravity in the following bodies.

A cone made of brass

ABCDE is a regular pentagon with its center of gravity at O. What will be the most probable position (W, X, Y, Z or O) of the new center of gravity:

1. if a piece of clay is attached at point A?
2. if the pentagon is cut along the line PQ? (Of the remaining part DCBQPE)

1. Can centre of gravity of a body be outside the body? If so give an example.
2. Draw the diagram for example in (a) clearly showing centre of gravity.

Define the following:

Circular motion

Define Centripetal force.

Define the term centrifugal force.

State whether following statement is true or false.

On the deformation of body (such as soft drink can), the position of centre of gravity does not change.

'The centre of gravity of a freely suspended body always lies vertically below the point of suspension'.

A stone of mass 'm' is rotated in a circular path with a uniform speed by tying a strong string with the help of your hand. Answer the following questions:

1. Is the stone moving with a uniform or variable speed?
2. Is the stone moving with a uniform or variable velocity?
3. Is the stone moving with a uniform or variable acceleration?
4. What is the effect of acceleration on the stone?
5. In which direction acceleration acts?
6. What kind of force is acting on the stone and state its direction?
7. What kind of force is acting on hand and state its direction?

Give an example of a body moving with uniform speed, but has an accelerated motion.

Differentiate between uniform linear motion and uniform circular motion.

State two differences between the centripetal and centrifugal force.

Explain movement of earth around the sun.

Explain movement of electrons around the nucleus.

The point of action of force on a rigid body is:

The turning effect produced in a rigid body around a fixed point by the application of force is called ______.

The unit of moment of force in SI system is ______.

A moment of couple has a tendency to rotate the body in an anticlockwise direction. Then the moment of the couple is taken as ______.

The condition for equilibrium is:

A body is acted upon by two equal and opposite forces along different lines of action of force. The body will have:

The centre of gravity of a cricket ball is at ______.

A body is describing a uniform circular motion. Which of the following quantities is/are constant?

In a uniform circular motion ______.

Two equal and opposite forces of 20 N are acting along the diameter of a wheel of radius 5 m. The moment of couple due to the forces is:

The diagram alongside shows a rigid body, such that force F acts at point P.

The line of action of force in this case is :

A door is easy to open or close if the force is applied ______.

In non-motorised steering wheels of the automobiles its diameter is kept large to provide ______.

The figure alongside shows a rigid body, capable of turning around point O.

If a force F, acts at point A, the moment of force of F around O is :

In S.I. system, gravitational unit of moment is kilogram force metre, (kgf-m). One kgf-m in C.G.S. system is equal to:

The spanner used to tighten or loosen a nut of the automobile wheel, has long handle, because long handle ______.

In order to cause the motion of rotation in rigid pivoted body there must act:

According to principle of moments:

For a triangular lamina the centre of mass (centre of gravity) is the ______.

The centripetal force and centrifugal force act on the ______.

The mud flies off the wheels of a moving vehicle because of ______.

A pendulum is made to swing in an evacuated chamber. The pendulum while swinging in the state of:

A brass ball is suspended by a strong cotton thread is not moving. On the brass ball:

A boy of mass 30 kg is sitting at distance of 2 m from the middle of see-saw. The moment of force generated by the boy is:

In the diagram alongside the moment of couple around point R is :

In the diagram alongside, F₁ = F₂ acting on a wheel of radius 2.5 m produce a moment of couple of 100 Nm. The magnitude of each force acting on the wheel is:

A uniform half metre-scale of weight W is balanced by a weight of 50 gf. The magnitude of weight W is :

Assertion (A): The turning effect on the body about an axis is due to the moment of force (torque) applied on the body.

Reason (R): The moment of a force (torque) is equal to the product of the magnitude of the force and the perpendicular distance of the line of action of the force from the axis of rotation.