Q1. A ball is thrown upwards in a train which is accelerating. The ball will fall
(a) Ahead of the thrower
(b) Behind the thrower
(c) In the hands of thrower
(d) Data inadequate
Q2. A moving bullet hits a solid target resting on a friction less surface and gets embedded in it. What is conserved in this process?
(a) Both momentum and kinetic energy
(b) Kinetic energy alone
(c) Momentum alone
(d) Neither momentum nor kinetic energy
Q3. The good absorbers of heat are:
(a) Poor emitters
(c) Good emitters
(d) Highly polished
Q4. A piece of metal feels hotter than a piece of wood in summer because:
(a) Metal expands more than wood
(b) Our body is cooler than metal but warmer than wood
(c) Metal is a better conductor of heat than wood
(d) Metal gets hotter than wood
Q5. Heat produced in a conductor depends on:
(a) Directly on time
(b) Inversely on time
(c) Both (a) and (b) are true
(d) None of the above
Q6. Sound waves do not show in air:
Q7. Velocity of sound will be:
(a) Slower in moist air than in dry air
(b) Faster in moist air than in dry air
(c) Same in moist and dry air
(d) Independent of its density
Q8. Buzzing of a mosquito is:
(a) Loud should
(b) Shrill sound
(c) Flat sound
(d) Sweet sound
Q9. Doppler’s effect of sound is produced when the source and the observer are:
(b) In relative motion
(d) Resonance phenomenon
Q10. The same notes being played on the sitar and veena differ in:
(c) Both pit hand quality
(d) None of the two
Sol. The reason is that at the moment the ball was thrown, the ball was in motion along with the person and the train, due to the inertia of motion. So during the time ball remains in air, both the person and the ball move ahead by the same distance. This makes the ball to come back to his hand on its return.
Sol. No external force is acting on the bullet + solid block system, thus linear momentum of the system is conserved. Also is it perfectly inelastic collision, so kinetic energy does not conserve. So, only momentum will conserve.
Sol. the ratio of emissive power to absorptive ratio was the same for all bodies emitting and absorbing thermal radiation in thermodynamic equilibrium. This means that a good absorber is a good emitter.
Sol. As moist will decrease the density of air particles at constant temperature and pressure. So the speed of sound will increase. Hence the sound will travel faster in moist air than the dry air.
Sol. The same note played on sitar and veena differ in their quality i.e., the number of harmonics present, their order and relatives intensities.