does not depend on the point about which you take the moments.

depends on the point about which you take the moments.

depends on the reference frame.

does not depend on the direction of the forces.

Physics - Systems Particles Rotational Motion - Quiz-14

Moment of a couple:

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depends on the point about which you take the moments.
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depends on the reference frame.
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does not depend on the point about which you take the moments.
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does not depend on the direction of the forces.

A metal bar 70 cm long and 4.00 kg in mass supported on two knife edges placed 10 cm from each end. A 6.00 kg load is suspended at 30 cm from one end as shown in the figure. The reactions $R_{1} and R_{2}$ at the knife-edges are:

(Assume the bar to be of uniform cross-section and homogeneous.)

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43.12 N and 54.88 N
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54.88 N and 4.312 N
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54.88 N and 43.12 N
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43.12 N and 5.488 N

A 3 m long ladder weighing 20 kg leans on a frictionless wall. Its feet rest on the floor 1 m from the wall as shown in the figure. The reaction forces of the wall and the floor respectively are:

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30.4 N and 198 N
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199 N and 30 N
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30 N and 199 N
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34.6 N and 199 N

The moment of inertia of a disc about one of its diameters is:

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${MR}^{2}$
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$\frac{{MR}^{2}}{3}$
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$\frac{2 {MR}^{2}}{3}$
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$\frac{{MR}^{2}}{4}$

The moment of inertia of a rod of mass M, length l about an axis perpendicular to it through one end is:

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${Ml}^{2}$
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$\frac{{Ml}^{2}}{2}$
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$\frac{{Ml}^{2}}{3}$
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Can't be determined

The moment of inertia of a ring about a tangent to the circle of the ring is:

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${MR}^{2}$
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$\frac{{MR}^{2}}{2}$
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$\frac{3 {MR}^{2}}{2}$
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$\frac{{MR}^{2}}{3}$

Angular velocity at any time t of a rotating body is given as $ω (t) = ω_{0} + at$ . Its Magnitude of angular acceleration:

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is always constant.
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increases with time.
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decreases with time.
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first increases then decreases with time.

A cord of negligible mass is wound round the rim of a fly wheel of mass 20 kg and radius 20 cm. A steady pull of 25 N is applied on the cord as shown in figure. The flywheel is mounted on a horizontal axle with frictionless bearings. The angular acceleration of the wheel is?

735

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12.5 $rad / s^{2}$
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10.5 $rad / s^{2}$
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1.25 $rad / s^{2}$
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9.25 $rad / s^{2}$

A cord of negligible mass is wound round the rim of a flywheel of mass 20 kg and radius 20 cm. A steady pull of 25 N is applied on the cord as shown in the figure. The flywheel is mounted on a horizontal axle with frictionless bearings. The work done by the pull, when 2m of the cord is unwound is:

735

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20 J
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30 J
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100 J
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50 J

A cord of negligible mass is wound round the rim of a flywheel of mass 20 kg and radius 20 cm. A steady pull of 25 N is applied on the cord as shown in the figure. The flywheel is mounted on a horizontal axle with frictionless bearings. The kinetic energy of the wheel when 2 m of the cord is unwound? Assume that the wheel starts from rest.

735

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5 J
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10 J
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500 J
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50 J

Three bodies, a ring, a solid cylinder and a solid sphere roll down the same inclined plane without slipping. They start from rest. The radii of the bodies are identical. Which of the bodies reaches the ground with maximum velocity?

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Ring
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Solid cylinder
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Solid sphere
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All bodies will reach the ground with the same speed

From a circular ring of mass "M" and radius "R", an arc corresponding to a 90 $°$ sector is removed. The moment of inertia of the remaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is 'K' times $' {MR}^{2}'$ . The value of 'K' will be:

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$\frac{1}{4}$
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$\frac{1}{8}$
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$\frac{3}{4}$
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$\frac{7}{8}$

A uniform rod of length 200 cm and mass 500 g is balanced on a wedge placed at 40 cm mark. A mass of 2 kg is suspended from the rod at 20 cm and another unknown mass 'm' is suspended from the rod at 160 cm mark as shown in the figure. Find the value of 'm' such that the rod is in equilibrium. (g=10 m/s²)

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$\frac{1}{6} kg$
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$\frac{1}{12} kg$
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$\frac{1}{2} kg$
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$\frac{1}{3} kg$

A cord is wound round the circumference of wheel of radius r. The axis of the wheel is horizontal and the moment of inertia about it is I. A weight mg is attached to the cord at the end. The weight falls from rest. After falling through a distance 'h', the square of angular velocity of wheel will be :

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$\frac{2 m g h}{I + 2 m r^{2}}$
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$\frac{2 mgh}{I + {mr}^{2}}$
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2gh
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$\frac{2 gh}{I + {mr}^{2}}$

The center of mass is defined as $\vec{R}=\frac{1}{M} \sum_{i} m_{i} \overrightarrow{r_{i}}.$. Suppose we define "center of charge" as $\vec{R}_{c}=\frac{1}{Q} \sum_{i} q_{i} \vec{r}_{i}$ where q_i represents the ith charge placed at $\vec r_i$ and Q is the total charge of the system. center of charge of a two-charge system

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May be inside the line segment joining charges
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May be outside the line segment joining charges
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May be outside the line segment joining charges
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Both (1) & (2)

If the linear momentum of a particle is known, We can find

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Kinetic energy
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Potential energy
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Torque acting on the particle
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Both (1) & (2)

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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