Given below are two statements : one is labelled as Assertion A a… - Vidyadip

MCQ

Given below are two statements : one is labelled as Assertion $A$ and the other is labelled as Reason $R.$

Assertion $A :$ Moment of inertia of a circular disc of mass $'M'$ and radius $'R'$ about $X, Y$ axes (passing through its plane) and $Z-$axis which is perpendicular to its plane were found to be $I_{x}, I_{y}$ and ${I}_{z}$ respectively. The respective radii of gyration about all the three axes will be the same.

Reason $R$ : A rigid body making rotational motion has fixed mass and shape.

In the light of the above statements, choose the most appropriate answer from the options given below :

A
Both $A$ and $R$ are correct but $R$ is NOT the correct explanation of $A$.
✓
$A$ is not correct but $R$ is correct.
C
$A$ is correct but $R$ is not correct.
D
Both $A$ and $R$ are correct and $R$ is the correct explanation of $A$.

✓

Answer

Correct option: B.

$A$ is not correct but $R$ is correct.

b
$I_{z}=I_{x}+I_{y}$ (using perpendicular axls theorem)

$l = mk ^{2}$ (K: radius of gyratlon)

so $m K_{z}^{2}=m K_{x}^{2}+m K_{y}^{2}$

$K_{z}^{2}=K_{x}^{2}+K_{y}^{2}$

so radius of gyration about axes $x, y$ and $z$ won't be same hense asseration $A$ is not correct reason $R$ is correct statement (property of a rlgid body)

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 6. system of particles and rotational motion→6. system of particles and rotational motion — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

The time period of an earth satellite in circular orbit is independent of:

The kinetic energy and potential energy of a particle executing simple harmonic motion will be equal, when displacement (amplitude = $a$) is

A monoatomic gas of $n-$moles is heated from temperature $T‌_1$ to $T_2$ under two different conditions $(i)$ at constant volume and $(ii)$ at constant pressure. The change in internal energy of the gas is

If a body of mass $M$ collides against a wall with velocity $V$ and rebounds with the same speed, then its change of momentum will be:

To keep constant time, watches are fitted with balance wheel made of

A wire $2 \,m$ in length suspended vertically stretches by $10 \,mm$ when mass of $10 \,kg$ is attached to the lower end. The elastic potential energy gain by the wire is ...... $J$ (take $g=10 \,m / s ^2$ )

$\Delta U + \Delta W = 0$ is valid for

A massless spring $(k = 800\, N/m)$, attached with a mass $(500\, g)$ is completely immersed in $1\, kg$ of water. The spring is stretched by $2\, cm$ and released so that it starts vibrating. What would be the order of magnitude of the change in the temperature of water when the vibrations stop completely? (Assume that the water container and spring receive negligible heat and specific heat of mass $= 400\, J/kg\, K$, specific heat of water $= 4184\, J/kg\, K$)

A cubical block of wood of specific gravity $0.5$ and a chunk of concrete of specific gravity $2.5$ are fastened together. The ratio of the mass of wood to the mass of concrete which makes the combination to float with its entire volume submerged under water is

The heat radiated per unit area in $1\,hour$ by a furnace whose temperature is $3000\,K$ is $( \sigma = 5. 7 \times 10^{-8}\,W\,m^{-2}\,K^{-4})$