A drum of radius R and mass M, rolls down without slipping along an inclined plane of angle θ. The frictional force

• converts translational energy to rotational energy

• dissipates energy as heat

• decreases the rotational motion

• decreases the rotational and translational motion

A block B is pushed momentarily along a horizontal surface with an initial velocity v. If µ is the coefficient of sliding friction between B and the surface, block B will come to rest after a time

• $\frac{\mathrm{\nu }}{\mathrm{g\mu }}$

• $\frac{\mathrm{g\mu }}{\mathrm{\nu }}$

• $\frac{\mathrm{g}}{\mathrm{\nu }}$

• $\frac{\mathrm{\nu }}{\mathrm{g}}$

Diwali rocket is ejecting 50 g of gases/s at a velocity of 400 m/s. The accelerating force on the rocket will be

• 22 dyne

• 20 N

• 20 dyne

• 100 N

A weightless thread can bear tension upto 37 N. A stone of mass 500 g is tied to it and revolved in a circular path of radius 4 min a vertical plane. If g = 10 ms^-2,  then the maximum angular velocity the stone will be

• 2 rad s^-1

• 4 rad s^-1

• 8 rad s^-1

• 16 rad s^-1

A bullet of mass 20 g and moving with 600 m/s collides with a block of mass 4 kg hanging with the string. What is velocity of bullet when it comes out of block, if block rises to height 0.2 m after collision?

• 200 m/s

• 150 m/s

• 400 m/s

• 300 m/s

Voltage in the secondary coil of a transformer does not depend upon

• frequency of the source

• voltage in the primary coil

• ratio of number of turns in the two coils

• Both (b) and (c)

A shell of mass 20 kg at rest explodes into two fragments whose masses are in the ratio 2 : 3. The smaller fragment moves with a velocity of 6 m/s. The kinetic energy of the larger fragment is

• 96 J

• 216 J

• 144 J

• 360 J

An electric bulb has a rated power of 50 W at 100 V. If it is used on an AC source 200 V, 50 Hz, a choke has to be used in series with it. This choke should have an inductance of

• 0.1 mH

• 1 mH

• 0.1 mH

• 1.1 H

Three concurrent co-planar forces 1 N, 2 N and 3 N acting along different directions on a body

• can keep the body in equilibrium if 2 N and 3 N act at right angle

• can keep the body in equilibrium if 1 N and 2 N act at right angle

• cannot keep the body in equilibrium

• can keep the body in equilibrium in 1 N and 3 N act at an acute angle

Two rectangular blocks A and B of masses 2 kg and 3 kg respectively are connected by a spring of constant 10.8 Nm^-1 and are placed on a frictionless horizontal surface. The block A was given an initial velocity of 0.15 ms^-1 in the direction shown in the figure. The maximum compression of the spring during the motion is

• 0.01 m

• 0.02 m

• 0.05 m

• 0.03 m