Exam
1 A body is falling freely under the action of gravity
alone in vacuum. Which of the following quantities
remain constant during fall?
(a) Kinetic energy
(b) Potential energy
(c) Total mechanical energy
(d) Total linear momentum
(d) the magnetic forces are necessarily negligible
2. An engine exerts a force F = (20i-3j+ 5k) N and moves with velocity v = ( (6i+ 20 - 3k) ms¹. The
power of the engine (in watt) is
(a) 45
(b) 75
(c) 20
(d) 10
3.Two masses of 1 g and 4 g are moving with equal kinetic energies. The ratio of the magnitudes
of their momenta is
(a) 4:1
(b) √2:1
(c) 1:2
(d) 1 : 16
4.The energy required to accelerate a car from rest to 10 m/s is W. The energy required to
accelerate the car from 10 ms¹ to 20 ms -¹ is
(a) W
(c) 3 W
, (b) 2 W
(d) 4 W
5.A car moving with a speed of 40 kmh -1 stopped by applying brakes in 2 m. If the car is can be
moving with a speed of 80 kmh, the minimum stopping distance under similar brakes will be
(a) 8 m
(b) 2 m
(c) 4 m
(d) 6 m
6.A long spring is stretched by 2 cm. Its potential energy is U. If the spring is stretched by 10
cm, its potential energy would be U
(a)u/25
(b) U/5
(c) 5U
7.When a force is applied at one end of an elastic wire, it produces a strain E in the wire. If Y is
the Young's modulus of the material of the wire, the amount of energy stored per unit volume of
the wire is given by
(a) Y x E
(b) 1/2(Y×E)
(c)(Y×E²)
(d)1/2(Y×E²)
8.If the Young's modulus of the material is 3 times its modulus of rigidity, then its volume
elasticity will be
(a) zero
(c) 2 x 10¹⁰ N/m²
(b) infinity
1 A body is falling freely under the action of gravity
alone in vacuum. Which of the following quantities
remain constant during fall?
(a) Kinetic energy
(b) Potential energy
(c) Total mechanical energy
(d) Total linear momentum
(d) the magnetic forces are necessarily negligible
2. An engine exerts a force F = (20i-3j+ 5k) N and moves with velocity v = ( (6i+ 20 - 3k) ms¹. The
power of the engine (in watt) is
(a) 45
(b) 75
(c) 20
(d) 10
3.Two masses of 1 g and 4 g are moving with equal kinetic energies. The ratio of the magnitudes
of their momenta is
(a) 4:1
(b) √2:1
(c) 1:2
(d) 1 : 16
4.The energy required to accelerate a car from rest to 10 m/s is W. The energy required to
accelerate the car from 10 ms¹ to 20 ms -¹ is
(a) W
(c) 3 W
, (b) 2 W
(d) 4 W
5.A car moving with a speed of 40 kmh -1 stopped by applying brakes in 2 m. If the car is can be
moving with a speed of 80 kmh, the minimum stopping distance under similar brakes will be
(a) 8 m
(b) 2 m
(c) 4 m
(d) 6 m
6.A long spring is stretched by 2 cm. Its potential energy is U. If the spring is stretched by 10
cm, its potential energy would be U
(a)u/25
(b) U/5
(c) 5U
7.When a force is applied at one end of an elastic wire, it produces a strain E in the wire. If Y is
the Young's modulus of the material of the wire, the amount of energy stored per unit volume of
the wire is given by
(a) Y x E
(b) 1/2(Y×E)
(c)(Y×E²)
(d)1/2(Y×E²)
8.If the Young's modulus of the material is 3 times its modulus of rigidity, then its volume
elasticity will be
(a) zero
(c) 2 x 10¹⁰ N/m²
(b) infinity
