Q:If the linear momentum of a body is increased by 50% then the kinetic energy of that body increases by
O: (a) 100% (b) 200%
(c) 225% (d) 25%
Ans. (b) 125%
Q: A body 2kg is thrown up vertically with kinetic energy of 490J. If g=9.8 ms-2, the height at which the kinetic energy of the body becomes half of the original value, is
O: (a) 50 m (b) 25m
(c) 12.5m (d) 19.6m
Ans. (c) 12.5m
Q: A rod of length L and mass m is kept vertically on the ground. Its potential energy is
O: (a) mgl (b) mgL/2
(c) mgL/3 (d) mgL/4
Ans. (b) mgL/2
Q: A bomb of 12kg explodes into two pieces of masses 4kg and 8kg mass is 6 ms-1. The kinetic energy of the other mass is
O: (a) 348J (b) 332 J
(c) 324J (d) 288J
Ans. (d) 288J
Q: If a sphere is rolling, then the ratio of its rotational kinetic energy to the total kinetic energy is
O: (a) 1:2 (b) 2:5
(c) 2:7 (d) 5:7
Ans. (c) 2:7
Q: A person, with outstretched arms, is spinning on a rotating stool. He suddenly brings his arms down to his sides. Which of the following is true about his kinetic energy K and angular momentum L?
O: (a) Both K and L increased. (b) Both K and L remain unchanged.
(c) K remains constant. (d) K increased but L remains constant.
Ans. (d) K increased but L remains constant.
Q: A gas is compressed adiabatically till its temperature is doubled. The ratio of its final volume will be
O: (a) 1/2 (b) more then 1/2
(c) less then 1/2 (d) between 1 and 2
Ans. (c) less then 1/2
Q: A resonance tube is resonated with tuning fork of frequency 256Hz. If the length of resonating air columns is 32cm and 100cm, then end correction will be
O: (a) 1cm (b) 2cm
(c) 4cm (d) 6cm
Ans. (b) 2cm
Q: An achromatic combination of lenses has the power of convex lens 2D and ratio of dispersive powers of lenses are equal then the focal length of concave lens is
O: (a) -50cm (b) 100cm
(c) 20cm (d) 200cm
Ans. (a) -50cm
Q: Half-life of a radioactive substance is 20 minute. The time between 20% and 80% decay will be
O: (a) 20 min (b) 30 min
(c) 40 min (d) 25 min
Ans. (c) 40 min
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