MCQ

MCQ 11 Mark

The centre of gravity of a hollow cone of height $h$ is at distance $x$ from its vertex where the value of $x$ is : ________ .

A
$\frac{ h }{3}$
B
$\frac{ h }{4}$
✓
$\frac{2 h }{3}$
D
$\frac{3 h }{4}$

Answer

Correct option: C.

$\frac{2 h }{3}$

The centre of gravity of a hollow cone is at a height $h / 3$ from the base. Hence, from the vertex the height is $h -\frac{ h }{3}=\frac{2 h }{3}$.
Hence, the correct answer $\frac{2 h }{3}$.

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MCQ 21 Mark

The centre of gravity of a uniform ball is
a) at its geometrical centre
b) at its bottom
c) at its topmost point
d) at any point on its surface

✓
at its geometrical centre
B
at its bottom
C
at its topmost point
D
at any point on its surface

Answer

Correct option: A.

at its geometrical centre

At its geometrical centre

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MCQ 31 Mark

A body is acted upon by two unequal forces in opposite directions, but not in the same line. The effect is that : ________ .

A
The body will have only the rotational motion
B
The body will have only the translational motion
C
The body will have neither the rotational motion nor the translational motion
✓
The body will have rotational as well as translational motion.

Answer

Correct option: D.

The body will have rotational as well as translational motion.

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MCQ 41 Mark

The moment of a force about axis depends : ________ .

A
Only on the magnitude of force
B
Only on the perpendicular distance of force from the axis
C
Neither on the force nor on the perpendicular distance of force from the axis
✓
Both on the force and its perpendicular distance from the axis.

Answer

Correct option: D.

Both on the force and its perpendicular distance from the axis.

The moment of a force about a given axis depends on both on the force and its perpendicular distance from the axis.

Moment of force = Force x Perpendicular distance

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MCQ 51 Mark

A door lock is opened by turning the lever (handle) of length 0.2 m . If the moment of force produced is 1 Nm , then the minimum force required is:

✓
5 N
B
10 N
C
20 N
D
0.2 N

Answer

Correct option: A.

5 N

(a) 5 N
Explanation :
Force $=\frac{\text { Momentofforce }}{\text { Lengthof lever }}$
$
=\frac{1}{0.2}=5 N
$

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MCQ 61 Mark

What occurs when a body is subjected to two unequal forces in opposite directions that are not aligned?

A
The body will only have rotational motion
B
The body will only have translational motion
C
The body will have neither rotational nor translational motion
✓
The body will have both rotational and translational motion

Answer

Correct option: D.

The body will have both rotational and translational motion

(d) The body will have both rotational and translational motion
Explanation:
When two unequal, misaligned forces act in opposite directions on a body, they generate both a rotational and a translational movement, resulting in combined motion due to the differing force magnitudes and points of application.

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MCQ 71 Mark

For maximum turning effect on a body by a given force, the perpendicular distance of the line of force from the axis of rotation should be:

A
Minimum
B
It does not matter
✓
Maximum
D
Zero

Answer

Correct option: C.

Maximum

(c) Maximum
Explanation:
Torque is maximized when the perpendicular distance from the axis of rotation to the line of action of the force is at its greatest. This distance amplifies the turning effect of the force applied.

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MCQ 81 Mark

On what factors does the moment of a force about a given axis depend?

A
Only on the magnitude of the force
B
Only on the perpendicular distance of the force from the axis
C
Neither the force nor the perpendicular distance of the force from the axis
✓
Both the force and its perpendicular distance from the axis

Answer

Correct option: D.

Both the force and its perpendicular distance from the axis

(d) Both the force and its perpendicular distance from the axis
Explanation:
The moment of a force (torque) about an axis is influenced by both the magnitude of the force applied and the perpendicular distance from the axis to the force's line of action, affecting its turning effect.

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MCQ 91 Mark

What type of motion does a door exhibit when force is applied to its handle?

✓
Rotational motion
B
Linear motion
C
Angular motion
D
Zigzag motion

Answer

Correct option: A.

Rotational motion

(a) Rotational motion
Explanation:
Rotational motion describes the movement of a body around a fixed axis. When force is applied to a door's handle, it pivots around its hinges, exhibiting rotational motion

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MCQ 101 Mark

What type of motion is exhibited by a stationary rigid body that begins moving in a straight path when a force is applied in its direction?

A
Rotational motion
✓
Linear motion
C
Angular motion
D
Zig-zag motion

Answer

Correct option: B.

Linear motion

(b) Linear motion
Explanation:
Linear motion occurs when an object moves along a straight path. This happens when a force is applied to a stationary rigid body in the direction of the force, causing the body to move linearly.

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MCQ 111 Mark

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

✓
positive
B
negative
C
maximum
D
zero

Answer

Correct option: A.

positive

(a) positive
Explanation:
Standard sign convention

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MCQ 121 Mark

S.I. unit of moment is:

A
kgf. M
✓
Nm
C
gf.m
D
Ncm

Answer

Correct option: B.

(b) Nm
Explanation:
Unit of moment of force $=$ Unit of force $\times$ Unit of distance
As the SI unit of force is newton and that of distance is metre, the SI Unit of moment is newton $\times$ metre ( Nm ).

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MCQ 131 Mark

A tap is used to fill bucket of water under a tap as shown in the figure. Name the force acting on the tap which produces rotational motion?

A
Centrifugal force
B
Centripetal force
✓
Couple
D
Tension force

Answer

Correct option: C.

Couple

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MCQ 141 Mark

A pole vaulter during Tokyo Olympics used a 2.5 m long rod which weighed 10 kg . If the mass of the pole vaulter was 65 kg , calculate the moment of force created by the pole vaulter?
$
\left[g=10 Nkg^{-1}\right]
$

A
162.5 kgm
✓
1625 Nm
C
16.25 Nm
D
1625 kgm

Answer

Correct option: B.

1625 Nm

(b) 1625 Nm
Explanation:
Moment of force $=$ Weight of athlete $\times$ Length of the pole.
$
\begin{array}{c}
=m g \times d \\
=65 \times 10 \times 2.5
\end{array}
$
$
=1625 Nm
$

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MCQ 151 Mark

A rectangular thin plate of dimension 3 m x 4 m is balanced on the fulcrum as shown below Find the resultant moment of force?

✓
9 Nm clockwise
B
9 Nm anticlockwise
C
5 Nm anticlockwise
D
6 Nm clockwise

Answer

Correct option: A.

9 Nm clockwise

(a) 9 Nm clockwise
Explanation:
The longer length is the length of rectangle at which 6 N force acts producing a clockwise moment while 5 N force acts along the breadth of the rectangle producing anticlockwise moments.
Resultant force = 6x4-5×3-24-15-9 N-m.

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MCQ 161 Mark

The resultant moment of couple, if two equal forces each of 6 N are acting at a distance of 3 cm each from the centre is:

A
36 Nm
B
360 Nm
C
3.6 Nm
✓
0.36 Nm

Answer

Correct option: D.

0.36 Nm

(d) 0.36 Nm
Explanation:
Resultant moment $=$ Clockwise moment + Anticlockwise moment
$
\begin{array}{l}
=0.03 \times 6+0.03 \times 6 \\
=0.18+0.18=0.36 Nm
\end{array}
$

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MCQ 171 Mark

The weight of half meter scale balanced at 5 cm mark when a weight of 10 gf is suspended at one of its ends is:

✓
2.5 gf
B
100 gf
C
0.2 gf
D
50 gf

Answer

Correct option: A.

2.5 gf

(a)2.5 gf
Explanation:

Let mass of metre rule be M.
Applying the principle of moments
Anticlockwise moment = Clockwise moment
$
\begin{array}{l}
Mg(25-5)=10 gf(5-0) \\
M=\frac{5 ggf}{20}=2.5 gf
\end{array}
$

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MCQ 181 Mark

$10^{-10} Nm$ is equal to ____________ dyne cm .

A
$10^{-4}$
B
10
✓
0.001
D
0.1

Answer

Correct option: C.

0.001

(c) 0.001
Explanation:
100 dyne $cm =10^{-5} Nm$
$1 Nm =100 \times 10^5$ dyne cm
$10^{-10} Nm =100 \times 10^5 \times 10^{-10}$ dyne cm
$10^{-10} Nm =0.001$ dyne cm

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MCQ 191 Mark

The maximum force required to open a nut by a spanner of length 50 cm producing a torque of 50 Nm is:

A
10 N
✓
100 N
C
0.1 N
D
None of these

Answer

Correct option: B.

100 N

(b) 100 N
Explanation:
Moment of force = Force x Perpendicular distance
$=50 / 0.50=100 N$

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MCQ 201 Mark

C.G. of a solid and hollow sphere are _______________ .

A
the same
B
different
✓
almost the same
D
geometric centre

Answer

Correct option: C.

almost the same

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MCQ 211 Mark

Centre of gravity is _______________ when it is a hollow cone.

✓
raised from the base
B
lower towards the base
C
centre of vertical axis
D
reduce from the base

Answer

Correct option: A.

raised from the base

(a) raised from the base
Explanation:
Lighter the object the more is the height of C.G. from the base.

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MCQ 221 Mark

A couple pair of forces keep the body in ______________ .

A
equilibrium
✓
no imbalance
C
rotational motion
D
both (b) and (c)

Answer

Correct option: B.

no imbalance

(b) no imbalance
Explanation:
Couple is responsible for rotational motion of an object.

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MCQ 231 Mark

Huge trailer trucks have their steering wheel of ___________ diameter.

✓
large
B
small
C
least
D
both (b) and (c)

Answer

Correct option: A.

large

(a) large
Explanation:
Larger couple arm, large is moment of couple.

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MCQ 241 Mark

Longer the size of the key ____________ it is to open a safe vault.

A
easier
B
lesser the force required by
C
convenient
✓
all of the above

Answer

Correct option: D.

all of the above

(d) all of the above
Explanation:
Increasing the length of key gives convenience, ease and force multiplication.

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MCQ 251 Mark

When a body moves in a circular path, outward force is called a _______________ .

A
Pseudo force
✓
Centrifugal force
C
Centripetal force
D
Reaction force

Answer

Correct option: B.

Centrifugal force

(b) Centrifugal force
Explanation:
Centrifugal force is not an actual force but a perceived force that appears to act outward on a body moving in a circular path when observed from a rotating frame of reference.

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MCQ 261 Mark

As a body moves in a circular path, inward seeking force is called _____________ .

A
Centrifugal force
B
Tension force
C
Tangential force
✓
Centripetal force

Answer

Correct option: D.

Centripetal force

(d) Centripetal force
Explanation:
Centripetal force is the net force causing the inward acceleration of a body moving in a circular path.

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MCQ 271 Mark

Uniform linear motion has _____________ .

A
constant speed, variable velocity
✓
constant speed, constant velocity
C
variable speed, constant velocity
D
variable speed, variable velocity

Answer

Correct option: B.

constant speed, constant velocity

(b) constant speed, constant velocity
Explanation:
Same speed and same direction as it is linear motion.

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MCQ 281 Mark

Uniform circular motion has ______________ .

✓
constant speed and variable velocity
B
variable speed and constant velocity
C
circular motion with uniform speed
D
variable speed and variable velocity

Answer

Correct option: A.

constant speed and variable velocity

(a) constant speed and variable velocity
Explanation:
Speed constant but direction variable hence variable velocity.

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MCQ 291 Mark

The C.G of a regular object will depend on __________ .

✓
distribution of mass
B
volume of the body
C
density of the body
D
all of the above

Answer

Correct option: A.

distribution of mass

(a) distribution of mass
Explanation:
Centre of gravity does not depend on density and volume.

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MCQ 301 Mark

The C.G of a regular object would lie ______________ .

A
on the body
B
outside the body
C
inside the body
✓
all of the above

Answer

Correct option: D.

all of the above

(d) all of the above
Explanation:
For 2D objects it is on the body while in 3D objects it lies outside as well as inside the body.

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MCQ 311 Mark

For equilibrium _____________ sum of all moments is equal to _____________ sum of all anticlockwise moments.

A
arithmetic, arithmetic
✓
algebraic, algebraic
C
algebraic, arithmetic
D
arithmetic, algebraic

Answer

Correct option: B.

algebraic, algebraic

(b) algebraic, algebraic
Explanation:
Since moments are associated with a direction, they can be treated like vectors.

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MCQ 321 Mark

Clockwise moments are considered to be _____________ .

A
positive
✓
negative
C
zero
D
both (a) and (b)

Answer

Correct option: B.

negative

(b) negative
Explanation:
In standard convection clockwise moments are negative and counter clockwise moments are positive, but conventions can vary.

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MCQ 331 Mark

Lesser the force applied ____________ is the moment of force

A
greater
✓
lesser
C
equal
D
negligible

Answer

Correct option: B.

lesser

(b) lesser
Explanation:
Moment of force is directly proportional to force. Therefore, if the force applied is lesser, the moment of force is also lesser.

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MCQ 341 Mark

Moment of force is to __________ the distance of point of application of force and fulcrum.

A
inversely proportional
✓
directly proportional
C
not equal
D
equal

Answer

Correct option: B.

directly proportional

(b) directly proportional
Explanation:
Moment of force = Force×Perpendicular distance.

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