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A ball is released from a certain height. It loses 50% of its kinetic energy on striking the ground. It will attain a height again equal to

1) One fourth the initial height 2) Half the initial height 3) Three fourth initial height 4) None of these Answer: 2) Half the initial... View Article

Which of the following is a unit of energy

1) Unit 2) Watt 3) Horse Power 4) None Answer: 4) None Solution: Watt and Horsepower are units of power... View Article

A constant power P is applied to a car starting from rest. If v is the velocity of the car at time t, then

1) v ∝ t 2) v ∝ 1/t 3) v ∝ √t 4) v ∝ 1/√t Answer: 3) v ∝ √t... View Article

A 20 kg of ball moving with a velocity 6 ms^-1 collides with a 30 kg of ball initially at rest. If both of them coalesce, then the final velocity of the combined mass is

1) 6 ms-1 2) 5 ms-1 3) 3.6 ms-1 4) 2.4 ms-1 5) 1.2 ms-1 Answer: 4) 2.4 ms-1 Solution: From the law of conservation of momentum... View Article

A body of mass m₁ collides elastically with another body of mass m₂ at rest. If the velocity of m₁ after collision becomes 2/3 times its initial velocity, the ratio of their masses is

1) 1 : 5 2) 5 : 1 3) 5 : 2 4) 2 : 5 Answer: 2) 5 : 1 Solution: Final velocity, v1 = (2/3)u1 In elastic collision, The second ball... View Article

If the linear momentum is increased by 50%, then kinetic energy will be increased by

1) 50% 2) 20% 3) 125% 4) None of these Answer: 3) 125% Solution: Pfinal = Pinitial + (Pinitial x 50/100) = (3/2)Pinitial... View Article

A bomb of mass 3m kg explodes into two pieces of mass m kg and 2m kg. If the velocity of m kg mass is 16 m/s. The total kinetic energy released in the explosion is

1) 192 mJ 2) 96 mJ 3) 384 mJ 4) 768 mJ Answer: 1) 192 mJ Solution: The velocity of m kg = 16 m/s The velocity of 2m kg = v2 m/s... View Article

Assertion Power developed in circular motion is always zero. Reason Work done in case of circular motion is zero.

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

A bomb of mass 10 kg explodes into 2 pieces of mass 4 kg and 6 kg. The velocity of mass 4 kg is 1.5 m/s, the K.E. of mass 6 kg is …….

1) 3.84 J 2) 9.6 J 3) 3.00 J 4) 2.5 J Answer: 3) 3.00 J Solution: m1v1 + m2v2 = 0 (4) (1.5) + (6) (V2) = 0 6V2 = –... View Article

A nucleus at rest splits into two nuclear parts having same density and radii in the ratio 1:2. Their velocites are in the ratio

1) 2:1 2) 4:1 3) 6:1 4) 8:1 Answer: 4) 8:1 Solution: Applying the law of conservation of momentum m1v1 = m2v2 Mass of a part of the... View Article

From an automatic gun a man fires 240 bullet per minute with a speed of 360 km/h. If each weighs 20 g, the power of the gun is

1) 400 W 2) 300 W 3) 150 W 4) 600 W Answer: Solution: Solution: Power of gun = Total Kinetic Energy of fired bullet/... View Article

A metal ball of mass 2 kg moving with a velocity of 36 km/h has a head on collision with a stationary ball of mass 3 kg. If after the collision, the two balls move together, the loss in kinetic energy due to collision is

1) 40 J 2) 60 J 3) 100 J 4) 140 J Answer: 2) 60 J Solution: Metal ball mass = 2 kg Speed of metal ball (v1) = 36 km/h = 10 m/s Mass... View Article

A canon ball is fired with a velocity 200 m/sec at an angle of 60° with the horizontal. At the highest point of its flight it explodes into 3 equal fragments, one going vertically upwards with a velocity 100 m/sec, the second one falling vertically downwards with a velocity 100 m/sec. The third fragment will be moving with a velocity

1) 100 m/s in the horizontal direction 2) 300 m/s in the horizontal direction 3) 300 m/s in a direction making an angle of 60° with the... View Article

A ball hits the floor and rebounds after inelastic collision. In this case

1) The momentum of the ball just after the collision is the same as that just before collision 2) The mechanical energy of the ball remains the... View Article

A gun fires a bullet of mass 50 g with a velocity of 30 m sec^–1. Because of this the gun is pushed back with a velocity of 1 m sec^–1. The mass of the gun is

1) 15 kg 2) 30 kg 3) 1.5 kg 4) 20 kg Answer: 3) 1.5 kg Solution: Mass of bullet,mb = 50 g Velocity of bullet,vb= 30 m... View Article

A sphere collides with another sphere of identical mass. After collision, the two spheres move. The collision is inelastic. Then the angle between the directions of the two spheres is

1) 90o 2) 0o 3) 45o 4) Different from 90o Answer: 4) Different from 90o Solution: The collision will be 900 if the collision is... View Article

A shell initially at rest explodes into two pieces of equal mass, then the two pieces will

1) Be at rest 2) Move with different velocities in different directions 3) Move with the same velocity in opposite directions 4) Move with the... View Article

A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 m/s. 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: Applying the law of conservation of momentum m1v1 + m2v2 = 0 2... View Article

An ice cream has a marked value of 700 kcal. How many kilowatt-hour of energy will it deliver to the body as it is digested

1) 0.81 kWh 2) 0.90 kWh 3) 1.11 kWh 4) 0.71 kWh Answer: 1) 0.81 kWh Solution: We know, 1kcal = 103 Calorie = 4200 J = 4200/(3.6 x 106) kWh... View Article

If a body of mass 200 g falls from a height of 200 m and its total P.E. is converted into K.E. at the point of contact of the body with the earth surface, then what is the decrease in P.E. of the body at the contact (g = 10 m/ s²)

1) 200 J 2) 400 J 3) 600 J 4) 900 J Answer: 2) 400 J Solution: Potential Energy, P.E = mgh = 0.200kg x 10 m/s x 200 m = 400 J... View Article