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18 Oct 2021: The Hindu Analysis

UPSC Current Affairs Preparation: The Hindu Analysis Watch expert analysis of ‘The Hindu’ dated 18th Oct 2021. Important news and views to boost... View Article

Economy This Week (9th Oct to 15th Oct 2021)

Economy is an important part of the UPSC prelims and mains exams; this series titled ‘Economy This Week’ has been initiated to address the need... View Article

A body of mass 2 kg is moving with velocity 10 m/s towards east. Another body of same mass and same velocity moving towards north collides with former and coalesces and moves towards north-east. Its velocity is

1) 10 m/s 2) 5 m/s 3) 2.5 m/s 4) 5√2 m/s Answer: 4) 5√2 m/s Solution: Initial momentum = Final momentum = 2m x... View Article

In an inelastic collision, what is conserved

1) Kinetic energy 2) Momentum 3) Both (1) and (2) 4) Neither (1) and (2) Answer: 2) Momentum Solution: momentum is conserved but... View Article

If the momentum of a body is increased by 100%, then the percentage increase in the kinetic energy is

1) 150% 2) 200% 3) 225% 4) 300% Answer: 4) 300% Solution: Kinetic Energy (K.E) = p2/2m ( p = momentum, m = mass) Momentum is... View Article

A body moving with velocity v has momentum and kinetic energy numerically equal. What is the value of v

1) 2 m/s 2) √2 m/s 3) 1 m/s 4) 0.2 m/s Answer: 1) 2 m/s Solution: Momentum = Kinetic Energy mv = (1/2)mv2 v = 2 m/s... View Article

A 0.5 kg ball is thrown up with an initial speed 14 m/s and reaches a maximum height of 8.0 m. How much energy is dissipated by air drag acting on the ball during the ascent?

1) 19.6 Joule 2) 4.9 Joule 3) 10 Joule 4) 9.8 Joule Answer: 4) 9.8 Joule Solution: If there is no air drag then maximum height, H =... View Article

The decrease in the potential energy of a ball of mass 20 kg which falls from a height of 50 cm is

1) 968 J 2) 98 J 3) 1980 J 4) None of these Answer: 2) 98 J Solution: Decrease in the potential energy, ΔU = mgh = 20 x 9.8 x... View Article

If the water falls from a dam into a turbine wheel 19.6 m below, then the velocity of water at the turbine is (g = 9.8 m/s²)

1) 9.8 m/s 2) 19.6 m/s 3) 39.2 m/s 4) 98.0 m/s Answer: 2) 19.6 m/s Solution: Velocity of water at the turbine v = √2gh... View Article

A bullet is fired from a rifle. If the rifle recoils freely, then the kinetic energy of the rifle is

1) Less than that of the bullet 2) More than that of the bullet 3) Same as that of the bullet 4) Equal or less than that of the bullet... View Article

Two bodies with kinetic energies in the ratio of 4 : 1 are moving with equal linear momentum. The ratio of their masses is

1) 1 : 2 2) 1 : 1 3) 4 : 1 4) 1 : 4 Answer: 4) 1 : 4 Solution: E = p2/2m m ∝ 1/E (If momentum are constant) (m1/m2) =... View Article

If the K.E. of a particle is doubled, then its momentum will

1) Remain unchanged 2) Be doubled 3) Be quadrupled 4) Increase √2 times Answer: 4) Increase √2 times Solution: p... View Article

If the K.E of a body is increased by 300%, its momentum will increase by

1) 100% 2) 1560% 3) √300 % 4) 175% Answer: 1) 100% Solution: Initial K.E = 100% Final K.E = (300 + 100)% = 400 % So,... View Article

Two masses of 1g and 4g are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is

1) 4 : 1 2) √2 : 1 3) 1 : 2 4) 1 : 16 Answer: 3) 1 : 2 Solution: p = √2km ⇒ p ∝ √m... View Article

According to work-energy theorem, the work done by the net force on a particle is equal to the change in its

1) Kinetic energy 2) Potential energy 3) Linear momentum 4) Angular momentum 5) Acceleration Answer: 1) Kinetic energy Solution: ... View Article

A light and a heavy body have equal momenta. Which one has greater K.E

1) The light body 2) The heavy body 3) The K.E are equal 4) Data is incomplete Answer: 1) The light body Solution: E = p2/2m ... View Article

If a force F is applied on a body and it moves with a velocity v, the power will be

1) F × v 2) F/ v 3) F / v2 4) F × v2 Answer: 1) F × v Solution: Power = Work/time = F x (dx/dt) = F x v Power =... View Article

If we throw a body upwards with a velocity of 4 m/s, at what height does its kinetic energy reduce to half of the initial value (Taking g = 10 ms^–1)

1) 4m 2) 2 m 3) 1 m 4) 0.4 m Answer: 4) 0.4 m Solution: Initial Kinetic Energy, K= (1/2) mv2 = (1/2) m(4)2 = 8m Final... View Article

If the force and displacement of a particle in direction of force are doubled. Work would be

1) Double 2) 4 times 3) Half 4) 1/4 times Answer: 2) 4 times Solution: Work = Force × Displacement If the force and... View Article

A 50kg man with a 20 kg load on his head climbs up 20 steps of 0.25 m height each. The work done in climbing is

1) 5 J 2) 350 J 3) 100 J 4) 3430 J Answer: 4) 3430 J Solution: Work done to climb a height h = potential energy gained to reach the... View Article