Archives

The kinetic energy of a body becomes four times its initial value. The new momentum will be

1) same as the initial value 2) twice the initial value 3) thrice the initial value 4) half of its initial value Answer: 2) twice the... View Article

A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It rolls down a smooth surface to the ground, then climbs up another hill of height 30 m and height of 20 m above the ground. The velocity attained by the ball is

1) 40 ms-1 2) 20 ms-1 3) 10 ms-1 4) 10√30 ms-1 Answer: 1) 40 ms-1 Solution: A spherical ball of mass 20 kg is stationary at the top of a... View Article

A bomb of mass 3.0 kg explodes in the air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 ms^-1. The total energy imparted to the two fragments is

1) 1.07 kJ 2) 2.14 kJ 3) 2.4 kJ 4) 4.8 kJ Answer: 4) 4.8 kJ Solution: From law of conservation of momentum mv = m1v1 + m2v2 3 x 0 =... View Article

A bomb of mass 9 kg explodes into two parts. One part of mass 3 kg moves with velocity 16 m/s, then the kinetic energy of the other part is

1) 162 J 2) 150 J 3) 192 J 4) 200 J Answer: 3) 192 J Solution: Given, Mass of the bomb = 9 Kg Mass of smaller part = 3 kg Mass of... View Article

A spring gun of spring constant 90 Ncm^-1 is compressed 12 cm by a ball of mass 16 g. If the trigger is pulled, the velocity of the ball is

1) 50 ms-1 2) 9 ms-1 3) 40 ms-1 4) 60 ms-1 5) 90 ms-1 Answer: 5) 90 ms-1 Potential energy stored in the spring= kinetic energy of the... View Article

A river of salty water is flowing with a velocity of 2 ms^-1. If the density of the water is 1.2 g/cc, then the kinetic energy of each cubic metre of water is

1) 2.4 J 2) 24 J 3) 2.4 kJ 4) 4.8 kJ Answer: 3) 2.4 kJ Solution: Given, The velocity of water, v = 2 m/s Density of... View Article

A 16 kg block moving on a frictionless horizontal surface with a velocity of 4 m/s compresses an ideal spring and comes to rest. If the force constant of the spring be 100 N/m, then the spring is compressed by

1) 1.6 m 2) 4 m 3) 6.1 m 4) 3.2 m Answer: 1) 1.6 m Solution: Kinetic energy of the block, K = (1/2)mv2 The kinetic energy will be... View Article

If the kinetic energy of a body is increased two times, its momentum will

1) half 2) remain unchanged 3) be doubled 4) Increases √2 times Answer: 4) Increases √2 times Solution: K =... View Article

A body of mass 5 kg is thrown vertically up with a kinetic energy of 490 J. The height at which the kinetic energy of the body becomes half of the original value is

1) 12.5 m 2) 10 m 3) 2.5 m 4) 5 m Answer: 4) 5 m Solution: Let h be the height at which kinetic energy of the body becomes half... View Article

Potential energy of a particle is related to x coordinate by equation x² – 2x will be equilibrium at

1) x = 0.5 2) x = 2 3) x = 1 4) x = 4 Answer: 3) x = 1 Solution: For stable equilibrium, Fnet = 0 F = - dU/dx F = -d(x2 -... View Article

Two balls of masses 2 g and 6 g are moving with kinetic energy in the ratio of 3: 1. What is the ratio of their linear momenta?

1) 1: 1 2) 2: 1 3) 1: 2 4) None of these Answer: 1) 1 : 1 Solution: Kinetic energy , K= (1/2)mv2 = (1/2) x m (mv2/m) = m2v2/2m K= p2/2m... View Article

A cubical vessel of height 1 m is full of water. What is the amount of work done in pumping water out of the vessel? (take, g =10 ms^-2)

1) 1250 J 2) 5000 J 3) 1000 J 4) 2500 J Answer: Mass of water in the cubical vessel= density x volume m = v x ρ = l3... View Article

A ball dropped from a height of 2 m rebounds to a height of 1.5 m after hitting the ground. Then, the percentage of energy lost is

1) 25 2) 30 3) 50 4) 100 Answer: 1) 25 Solution: Percentage of energy loss = [mg (2 - 1.5)/mgh] x 100 = [mg (2 - 1.5)/mg x 2] x 100 = 25%... View Article

The magnitude of momentum of particle is increased by 100%. The increase in its kinetic energy is

1) 100% 2) 200% 3) 300% 4) 400% Answer: 3) 300% Solution: Kinetic Energy, K.E = p2/2m p = momentum m = mass Momentum is... View Article

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 ms^-1. The kinetic energy of the larger fragment is

1) 96 J 2) 216 J 3) 144 J 4) 360 J Answer: 1) 96 J Solution: The ratio of the two masses is 2:3 Masses of the fragments are 8Kg and... View Article

A rod AB of mass 10 kg and length 4 m rests on a horizontal floor with end A fixed so, as to rotate it in a vertical plane about a perpendicular axis passing through A. If the work done on the rod is 100 J, the height to which the end B be raised vertically above the floor is

1) 1.5 m 2) 2 m 3) 1 m 4) 2.5 m 5) 3 m Answer: 2) 2 m Solution: Work done, W = mgh/2 100 = (10 x 10 x h)/2 100 = (100 x h)/2 h = 2m... View Article

A spring of spring constant 5 x 10³ Nm^-1 is stretched initially by 5 cm from the unstretched position. Then the work required to stretch it further by another 5 cm is

1) 12.50 N–m 2) 18.75 N–m 3) 25 N–m 4) 6.25 N–m Answer: 2) 18.75 N–m Solution: Work done, W1 = (1/2) k... View Article

The area under the displacement-force curve gives

1) distance travelled 2) total force 3) momentum 4) work done Answer: 4) work done Solution: Work done = force × displacement ... View Article

PM MITRA Parks [Govt Schemes for UPSC]

The government has approved the setting up of seven PM MITRA Parks with an outlay of Rs. 4,445 crores for over five years. In this article, you... View Article

if-the-sides-of-a-triangle-are-produced-in-order-prove-that-the-sum-of-the-exterior-angles-so-formed-is-equal-to-four-right-angles

Solution: The triangle ABC in which the sides AB, BC and CA produced to points F, D, and E. We have to prove that ∠DCA + ∠FAE + ∠FBD = 3600.... View Article