CBSE
Multiple Choice QuestionsThree 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
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)
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
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
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 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
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
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
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
