# Static Equilibrium

## Trending Questions

**Q.**

A uniform meter rule balances horizontally on a knife-edge placed at the 58 cm mark when a weight of 20 gf is suspended from one end.

(i) Draw a diagram of the arrangement.

(ii) What is the weight of the rule?

**Q.**

Describe a simple experiment to veryfy the principle of moments, if you are supplied with a metre rule, a fulcrum and two springs with slotted weights.

**Q.**

Fig. 1.33 shows a uniform metre rule placed on a fulcrum at its mid-point O and having a weight 40 gf at the 10 cm mark and a weight of 20 gf at the 90 cm mark. (i) Is the metre rule in equilibrium ? If not, how will the rule turn ? (ii) How can the rule be brought in equilibrium by using an additional weight of 40 gf ?

**Q.**

A physical balance has its arms of length 60 cm and 40 cm. What weight kept on pan of longer arm will balance an object of weight 100 gf kept on other pan ?

**Q.**

State the principle of moments. Name one device based on it.

**Q.**

State Newton's third law of motion. Give an example.

**Q.**The necessary condition for equilibrium of a body is

- algebraic sum of all the forces must be zero
- algebraic sum of all forces and moments of forces must be zero.
- algebraic sum of all the moments of force must be zero
- None of the above

**Q.**

Essential characteristic of equilibrium is

momentum equals to zero

acceleration equals to zero

K.E equals to zero

velocity equals to zero

**Q.**Newton’s third law of motion explains the two forces namely ‘action’ and ‘reaction’ coming into action when the two bodies in contact with each other.These two forces:

- always act on the same body.
- always act on different bodies in opposite directions.
- have the same magnitude and direction.
- always act on different bodies in the same direction.

**Q.**A uniform meter scale is in equilibrium as shown in figure.

Find the weight of the scale.

- 30 gf
- 40 gf
- 60 gf
- 50 gf

**Q.**

Action and reaction forces do not balance each other. Why?

**Q.**

Newton’s third law of motion states that for every action, there is an equal and opposite reaction. Which of the following statements can be inferred from the above-mentioned law of motion?

Statement 1: In every interaction, there is a pair of forces acting on the two interacting objects.

Statement 2: The size of the force on the first object equals the size of the force on the second object.

Statement 3: Forces always come in pairs - equal and opposite action-reaction force pairs.

Statement 4: Action and reaction act on the same body.

Statement 5: Action and reaction act on two different bodies.

All statements except 5 can be inferred from 3

^{rd}law of motionAll statements except 4 can be inferred from 3

^{rd}law of motionOnly statement 1 can be inferred from 3

^{rd}law of motionAll statements can be inferred from 3

^{rd}law of motion

**Q.**

Calculate the net moment on a rod of length 5m & mass 3000 g pivoted at 3 m from an end, if 2 weights of 500 gf & 800 gf are placed at 2 m & 4.5 m from the same end.

800 Nm Clockwise

800 gf.m Anti-clockwise

800 gf.m Clockwise

800 Nm Anti-clockwise

800 kgf.m Anti-clockwise

**Q.**A man is standing on a plank of weight 100 kgf pivoted at A and B as shown in figure. If the reaction force by pivot B is 66 kgf, find the weight of the man.

- 50 kgf
- 80 kgf
- 60 kgf
- 70 kgf

**Q.**

What are Static problems?

**Q.**

For a book lying on a table, the downward weight gets balanced by

normal reaction from the book to the table

the applied horizontal force

the diagonal applied force

normal reaction from the table to the book

**Q.**

The driver of a truck is taking a turn to the right. What are the signs ( +ve or -ve) of the moments applied by (a) right hand (b) left hand (c) both hands together?

The right hand will be negative, left hand will also be negative, and both the hands together will be positive

The right hand will be negative, left hand will also be negative, and both the hands together will also be negative

The right hand will be positive, left hand will also be positive, and both hands together will be negative

The right hand will be positive, left hand will also be positive, and both the hands together will also be positive

**Q.**

Complete the following sentences :

(i) The S.I. unit of moment of force is

(ii) In equilibrium, algebraic sum of moments of all forces about the point of rotation is

(iii) In a beam balance when the beam is balanced in a horizontal position, it is in

(iv) The moon revolving around the earth is in

**Q.**

The forces of action and reaction have_____magnitude but_____ direction.

same, same

same, opposite

opposite, same

opposite, opposite

**Q.**

A uniform metre rule balances horizontally on a knife edge placed at the 58 cm mark when a weight of 20 gf is suspended from one end.

(i) Draw a diagram of the arrangement.

(ii) What is the weight of the rule ?

**Q.**

A 4 m long rod of negligible weight is supported at a point 125 cm from its one end and a load of 18 kgf is suspended at a point 60 cm from the support on the shorter arm.

(a) if a weight W is placed at a distance of 250 cm from the support on the longer arm, find W.

(b) If a weight 5 kgf is kept to balance the rod, find the position.

(c) To which class of lever does it belong?

**Q.**

For the following baseball bat, where should we keep the fulcrum so as to balance it in a horizontal condition?

Close to the left end as per the diagram.

Close to the right end as per the diagram.

At center

Outside the bat

**Q.**In a beam balance, when the beam is balanced in a horizontal position, it is in ______.

**Q.**A body covers 12m in 2nd sec. and20m in 4th sec. the distance the body will cover in first 4sec. Is

**Q.**

A ball is placed in a trough as shown. This can be categorised as :

Stable Equilibrium

Unstable Equilibrium

Neutral Equilibrium

None of these

**Q.**Speeds of two identical cars are u and 4u at a specified instant the ratio of the respective distance at which the two cars are stopped from that instant age

**Q.**

A uniform meter rod is balanced in a horizontal position. It is an example of

mass equilibrium

dynamic equilibrium

static equilibrium

accelerated equilibrium

**Q.**

A ball is placed in a trough as shown. This can be categorised as?

Unstable Equilibrium

Stable Equilibrium

Neutral Equilibrium

Can not be said

**Q.**A ball is placed in a trough as shown. This can be categorised as?

- Unstable Equilibrium
- Stable Equilibrium
- Neutral Equilibrium

**Q.**A uniform meter scale is in equilibrium as shown in figure.

Find the weight of the scale.

- 30 gf
- 40 gf
- 50 gf
- 60 gf