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

A 0.5 kg ball is thrown up with an initial speed 14 m/s and reaches a maximum height of 8.0m. 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

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

A running man has half the kinetic energy of that of a boy of half of his mass. The man speeds up by 1m/s so as to have same K.E. as that of the boy. The original speed of the man will be 

(1) $\sqrt{2}m/s$

(2) $(\sqrt{2}-1)m/s$

(3) $\frac{1}{(\sqrt{2}-1)}m/s$

(4) $\frac{1}{\sqrt{2}}m/s$ 

A particle of mass m at rest is acted upon by a force F for a time t. Its Kinetic energy after an interval t is 

(1) $\frac{F^2{t}^2}{m}$

(2) $\frac{F^2{t}^2}{2m}$

(3) $\frac{F^2{t}^2}{3m}$

(4) $\frac{Ft}{2m}$

Two bodies of masses m and 4 m are moving with equal K.E. The ratio of their linear momentums is

(1) 4 : 1

(2) 1 : 1

(3) 1 : 2

(4) 1 : 4

A stationary particle explodes into two particles of masses m₁ and m₂ which move in opposite directions with velocities v₁ and v₂. The ratio of their kinetic energies E₁/E₂ is 

(1) m₁/m₂

(2) 1

(3) m₁ v₂/m₂ v₁

(4) m₂/m₁

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

A particle of mass m₁ is moving with a velocity v₁ and another particle of mass m₂ is moving with a velocity v₂. Both of them have the same momentum but their different kinetic energies are E₁ and E₂ respectively. If m₁ > m₂ then 

(1) E₁ < E₂

(2) $\frac{E_1}{E_2}=\frac{m_1}{m_2}$

(3) E₁ > E₂

(4) E₁ = E₂

Four particles are given, having same momentum. Which one has maximum kinetic energy- 

(1) Proton

(2) Electron

(3) Deutron

(4) α-particles