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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

The slope of the kinetic energy versus position vector curve gives the rate of change of

1) Momentum 2) velocity 3) Force 4) Power Answer: 1) Momentum Solution: Slope = dK.E/dx = mv (dv/dx) = mv (dv/dt) x (dt/dx) = mv... View Article

The work done against gravity in taking 10 kg mass at 1m height in 1 sec will be

1) 49 J 2) 98 J 3) 196 J 4) None of these Answer: 2) 98 J Solution: Work done = mgh = 10 x 9.8 x 1 = 98 J... View Article

A force of 5N acts on a 15kg body initially at rest. The work done by the force during the first second of motion of the body is

1) 5J 2) (⅚) J 3) 6J 4) 75J Answer: 2) (⅚) J Solution: Force, F = ma 5 = 15a a = (1/3) m/s2 Since, S = ut + (1/2)at2 S = 0 + (1/2)... View Article

A man pushes a wall and fails to displace it. He does

1) Negative work 2) Positive but not maximum work 3) No work at all 4) Maximum work Answer: 3) No work at all Solution: Work = Force x... View Article

If the unit of force and length each be increased by four times, then the unit of energy is increased by

1) 16 times 2) 8 times 3) 2 times 4) 4 times Answer: 1) 16 times Work = Force x Displacement If the unit of force and length is increased by four... View Article

A body of mass 1 kg is thrown upwards with a velocity 20 m/s. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction (g = 10 m / s²)

1) 20 J 2) 30 J 3) 40 J 4) 10 J Answer: 1) 20 J Solution: The energy lost due to the air friction will be equal to the difference in... View Article

Assertion The apparent weight of a body in an elevator moving with some downward acceleration is less then the actual weight of body. Reason The part of the weight is spent in producing downward acceleration, when body is in elevator.

1) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion. 2) If both Assertion and Reason are true... View Article

Assertion A reference frame attached to earth is an inertial frame of reference. Reason The reference frame which has zero acceleration is called a non-inertial frame of reference.

1) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion. 2) If both Assertion and Reason are true... View Article

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