Question
A ring and a solid sphere rotating about an axis passing through their centers have same radii of gyration. The axis of rotation is perpendicular to plane of ring. The ratio of radius of ring to that of sphere is $\sqrt{\frac{2}{x}}$. The value of $x$ is $.......$

Answer

For ring $I=m R_1^2=m K_1^2$

$\therefore$ Radius of gyration $K_1=R_1$

For solid sphere

$I^{\prime}=\frac{2}{5} m^{\prime} R_2^2=m^{\prime} K_2^2$

$\therefore \text { Its radius of gyration }=K_2=\sqrt{\frac{2}{5}} R_2$

$\because K_1=K_2$

$\therefore R_1=\sqrt{\frac{2}{5}} R_2$

$\therefore \frac{R_1}{R_2}=\sqrt{\frac{2}{5}}$

$\therefore x=5$

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

Similar questions

A person supports a book between his finger and thumb as shown (the point of grip is assumed to be at the corner of the book). If the book has a weight of $W$ then the person is producing a torque on the book of 
Spherical balls of radius $ 'r'$  are falling in a viscous fluid of viscosity '$\eta$' with a velocity $ 'v'. $ The retarding viscous force acting on the spherical ball is
Consider a Disc of mass $5 \mathrm{~kg}$, radius $2 \mathrm{~m}$, rotating with angular velocity of $10 \mathrm{rad} / \mathrm{s}$ about an axis perpendicular to the plane of rotation. An identical disc is kept gently over the rotating disc along the same axis. The energy dissipated so that both the discs continue to rotate together without slipping is ___________$J$.
What will be the angular momentum of a electron, if energy of this electron in $H-$atom is $1.5\,eV$ (in $J-sec$)
A ball is dropped from a height of $5\,\,m$  onto a sandy floor and penetrates the sand up to $1\,\,m$  before coming to rest. The retardation of the ball in sand (assuming it to be uniform) will be ................ $\mathrm{m}/ \mathrm{s}^2$
The current $I$, potential difference $V_L$ across the inductor and potential difference $V_C$ across the capacitor in circuit as shown in the figure are best represented vectorially as
A rod of length $l$ rotates with a uniform angular velocity $\omega $ about an axis passing through its middle point but normal to its length in a uniform magnetic field of induction $B$ with its direction parallel to the axis of rotation. The induced $emf$ between the two ends of the rod is
A force $F$ acting on an object varies with distance $x$ as shown here. The force is in $N$ and $x$ in $m$. The work done by the force in moving the object from $x = 0$ to $x = 6$ is ............. $\mathrm{J}$
A light ray traveling in glass medium is incident on glass-air interface at an angle of incidence $\theta$. The reflected $( R )$ and transmitted ( $T$ ) intensities, both as function of $\theta$, are plotted. The correct sketch is
A uniform wire of resistance $20\,ohm$ having resistance $1\Omega /m$ is bent in the adjoining form of a circle as shown in the figure. If the equivalent resistance between $M$ and $N$ is $1.8 \,\Omega $, then the length of the shorter section is ................ $m$