List of top Physics Questions on torque

A region in the form of an equilateral triangle (in x-y plane) of height L has a uniform magnetic field 𝐵⃗ pointing in the +z-direction. A conducting loop PQR, in the form of an equilateral triangle of the same height 𝐿, is placed in the x-y plane with its vertex P at x = 0 in the orientation shown in the figure. At 𝑡 = 0, the loop starts entering the region of the magnetic field with a uniform velocity 𝑣 along the +x-direction. The plane of the loop and its orientation remain unchanged throughout its motion.

Which of the following graph best depicts the variation of the induced emf (E) in the loop as a function of the distance (𝑥) starting from 𝑥 = 0?

The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by $50 \%$ The percentage change in voltage sensitivity of the galvanometer will be:

The torque acting on a magnetic dipole placed in uniform magnetic field is zero, when the angle between the dipole axis and the magnetic field is _____.

A metre scale is balanced on a knife edge at its centre. When two coins, each of mass 10 g are put one on the top of the other at the 10.0 cm mark the scale is found to be balanced at the 40.0 cm mark. The mass of the metre scale is found to be \(x\times 10^{-2}\) kg. The value of x is _________.

For forces are acting at a point P in equilibrium as shown in the figure. The ratio of force F₁ to F₂ is 1 : x where x =___.

When no external torque acts on a rotating system,

The magnitude of torque on a particle of mass $1\,kg$ is $2.5\, Nm$ about the origin. If the force acting on it is $1\, N$, and the distance of the particle from the origin is $5\,m$, the angle between the force and the position vector is (in radians) :

A ball of mass \(1\, kg\) and radius \(0.5\, m,\) starting from test rolls down on a \(30^{\circ}\) inclined plane. The torque acting on the ball at the distance of the \(7\, m\) from the starting point is close to
(Take: Acceleration due to gravity as \(10\, m/s^2\))

A solid cylinder of mass \(2 kg \) and radius \(4 cm\) is rotating about its axis at the rate of \( 3 rpm\). The torque required to stop after \(2\pi \)revolutions is: 

A hollow sphere and a solid sphere, of equal mass and equal radii roll down without slipping on an inclined plane. If the torque experienced by the hollow sphere and solid sphere are $\tau_H$ and $\tau_S$ respectively, then

A rigid metallic sphere is spinning around its own axis in the absence of external torque. If the temperature is raised, its volume increases by $9 \%$. The change in its angular speed is

A current carrying wire in its neighbourhood produces

Two thin circular discs of mass $m$ and $4\, m$, having radii of $a$ and $2 a$, respectively, are rigidly fixed by a massless, rigid rod of length $l=\sqrt{24}$ a through their centers. This assembly is laid on a firm and flat surface and set rolling without slipping on the surface so that the angular speed about the axis of the rod is $\omega$. The angular momentum of the entire assembly about the point 'O' is $\vec{ L }$ (see the figure). Which of the following statement(s) is(are) true?

The position vector $\vec{r}$ of a particle of mass $m$ is given by the following equation $\vec{r}(t)=\alpha t^{3} \hat{i}+\beta t^{2} \hat{j}$ where $\alpha=\frac{10}{3} \,ms ^{-3}, \beta=5\, ms ^{-2}$ and $m =0.1 \,kg$. At $t =1\, s$, which of the following statement (s) is (are) true about the particle?

The position vector $\vec{r}$ of a particle of mass $m$ is given by the following equation $\vec{r}(t)=\alpha t^{3} \hat{i}+\beta t^{2} \hat{j}$ where $\alpha=\frac{10}{3} \,ms ^{-3}, \beta=5\, ms ^{-2}$ and $m =0.1 \,kg$. At $t =1\, s$, which of the following statement (s) is (are) true about the particle?

An equilateral prism of mass $m$ rests on a rough horizontal surface with coefficient of friction $\mu$.

A horizontal force $F$ is applied on the prism as shown in the figure. If the coefficient of friction is sufficiently high so that the prism does not slide before toppling, then the minimum force required to topple the prism is -

A closely wound solenoid of $2000$ turns and area of cross-section $1.5 \times 10^{-4} m ^{2}$ carries a current of $2.0 A$. It is suspended through its center and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field $5 \times 10^{-2} T$, making an angle of $30^{\circ}$ with the axis of the solenoid. The torque on the solenoid will be

The torque of a force$\overrightarrow{F} = 2\hat{i} - 3\hat{j} +5\hat{k}$ acting at a point whose position vector $\overrightarrow{r} = 3\hat{i} - 3\hat{j} + 5\hat{k}$about the origin is

The instantaneous angular position of a point on a rotating wheel is given by the equation $\theta(t)=2t^3-6t^2$ The torque on the wheel becomes zero at

A torque of $ {{10}^{-5}}Nm $ is required to hold a magnet at $ 90{}^\circ $ with the horizontal component of the earths magnetic field. The torque required to hold it at $ 30{}^\circ $ will be

A closed loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments PS, SR and RQ are $F_1, F_2, $ and $ F_3$ respectively and are in the plane of the paper and along the directions shown, the force on the segment QP is

A particle of mass $m$ moves in the $XY$ plane with a velocity ' $v$ ' along the straight line $A B$. If the angular momentum of the particle with respect to origin $O$ is $L _{ A }$ when it is at $A$ and $L_{B}$ when it is at $B$, then

A constant torque acting on a uniform circular wheel changes its angular momentum from $A _{0}$ to $4 A _{0}$ in $4 \,s$. The magnitude of this torque is

A circular coil of $20$ turns and radius $10 \,cm$ is placed in uniform magnetic field of $ 0.10\,T $ normal to the plane of the coil. If the current in coil is $5 \,A$, then the torque acting on the coil will be

Two bodies have their moments of inertia I and 2I respectively about their axis of rotation. If their kinetic energies of rotation are equal, their angular momenta will be in the ratio