CBSE
Multiple Choice QuestionsA 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
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
A boy on a cycle pedals around a circle of 20 metres radius at a speed of 20 m/s. The combined mass of the body and the cycle makes with the vertical so that it may not fall is (g = 9.8 m/s2 )
60.25o
63.90o
26.12o
30.00o
