1. A list of mediums is given below.
(i) wood
(ii) water
(iii) air
(iv) vacuum
In which of these mediums can sound travel?
(a) i & ii only
(b) i, ii & iii only
(c) iii & iv only
(d) ii, iii & iv only
2. The loudness of a sound depends on:
(a) its amplitude.
(b) its frequency.
(c) its time period.
(d) its speed.
3. Which of the following statements are correct?
(i) Sound is produced by vibrations.
(ii) Sound requires a medium for propagation.
(iii) Light and sound both require a medium for propagation.
(iv) Sound travels slower than light.
(a) i & ii only
(b) i, ii & iii only
(c) ii, iii & iv only
(d) i, ii & iv only
4. An object is vibrating at 50 hertz. What is its time period?
(a) 0.02 s
(b) 2 s
(c) 0.2 s
(d) 20.0 s
5. In order to reduce the loudness of a sound, we have to
(a) decrease its frequency of vibration of the sound.
(b) increase its frequency of vibration of the sound.
(c) decrease its amplitude of vibration of the sound.
(d) increase its amplitude of vibration of the sound.
6. The loudness of sound is determined by the
(a) amplitude of vibration
(b) the ratio of amplitude and frequency of vibration
(c) frequency of vibration
(d) product of amplitude and frequency of vibration
7. 1 hertz is equal to
(a) 1 vibration per minute
(b) 10 vibrations per minute
(c) 60 vibrations per minute
(d) 600 vibrations per minute
8. Pitch of sound is determined by its
(a) frequency
(b) amplitude
(c) speed
(d) loudness
9. Ultrasound has a frequency of vibration
(a) between 20 and 20,000 Hz
(b) below 20 Hz
(c) above 20,000 Hz
(d) between 500 and 10,000 Hz
10. Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play
(a) only if the objects are solid.
(b) only if one of the two objects is liquid.
(c) only if one of the two objects is gaseous.
(d) irrespective of whether the objects are solid, liquid or gaseous.
11. To sharpen the blade of a knife by rubbing it against a surface, which of the following will be most suitable?
(a) stone
(b) plastic block
(c) wooden block
(d) glass block
12. If we apply oil on door hinges, the friction will
(a) increases
(b) decreases
(c) disappear altogether
(d) will remain unchanged
13. Which of the following statements is incorrect?
(a) Friction acts on a ball rolling along the ground.
(b) Friction acts on a boat moving on water.
(c) Friction acts on a bicycle moving on a smooth road.
(d) Friction does not act on a ball moving through air.
14. A boy rolls a rubber ball on a wooden surface. The ball travels a short distance before coming to rest. To make the same ball travel longer distance before coming to rest, he may
(a) spread a carpet on the wooden surface.
(b) cover the ball with a piece of cloth.
(c) sprinkle talcum powder on the wooden surface.
(d) sprinkle sand on the wooden surface
15. In a large commercial complex, there are four ways to reach the main road. One of the paths has loose soil, the second is laid with polished marble, the third is laid with bricks and the fourth has a gravel surface. It is raining heavily and Paheli wishes to reach the main road. The path on which she is least likely to slip is
(a) loose soil.
(b) polished marble.
(c) bricks.
(d) gravel.
16. Two boys are riding their bicycles on the same concrete road. One has new tyres on his bicycle while the other has tyres that are old and used. Which of them is more likely to skid while moving through a patch of the road which has lubricating oil spilt over it?
17. Imagine that an object is falling through a long straight glass tube held vertical; the air has been removed completely from the tube. The object does not touch the walls of the tube. Will the object experience any force of friction?
18. Lightning can be seen as the moment it occurs. Paheli observes lightning in her area. She hears the sound 5 s after she observed lightning. How far is she from the place where lightning occurs? (speed of sound = 330 m/s).
19. Boojho saw a cracker burst at night at a distance from his house. He heard the sound of the cracker a little later after seeing the cracker burst. Give the reason for the delay in hearing the sound.
20. A simple pendulum makes 10 oscillations in 20 seconds. What is the time period and frequency of its oscillation?
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