Question:
What travels faster : a rifle bullet or the sound of the shot fired from it ?
Answer:
Modem rifles are able to impart a velocity of about 900 m/s to a bullet which is about three times more than the speed of sound in air (340 m/s).Even if we take into account the air friction which retards the bullet,it still travels faster than sound.Thus,a bullet would have hit its victim before the sound of the shot reaches his ear.
Sound
Q 1.
Fill in the blanks :
If a body repeats its back and forth, to and fro or up and down motion along a certain path, about a fixed point, in a certain time interval then the motion of such objects is said to be _____________.
Q 2.
What is speed of sound in air?
Q 3.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 4.
What type of wave is represented by density- distance graph?
Q 5.
Distinguish between loudness and intensity of sound.
Q 6.
Fill in the blanks :
In the case of ____________ wave, distance between two consecutive crests or troughs is known as wavelength.
Q 7.
What is Sound? Why it is important for us?
Q 9.
What are ultrasonics?
Q 10.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 11.
What is reverberation?
Q 12.
What is audible range ?
Q 13.
Fill in the blanks :
RADAR (Radio Detection And Ranging) works on _____________ principle which is used to determine the velocities and movement of aircrafts.
Q 14.
Why are the ceilings of concert halls curved ?
Q 15.
How is ultrasound used for cleaning ?
Q 16.
Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound.Mark the position of compression and rarefaction on this curve.Also define wavelengths and time period using this curve.
Q 17.
What is infrasonic? Give an example.
Q 18.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 19.
An engine is approaching a hill at constant speed.When it is at a distance of 0.9 km,it blows a whisde,whose echo is heard by the driver after 5 s.If the speed of sound is 340 m/s,calculate the speed of the engine.
Q 20.
Distinguish between loudness and intensity of sound.
Q 21.
Cite an experiment to show that sound needs a material medium for its propagation.
Q 23.
How can you make a building sound proof ?
Q 24.
Fill in the blanks :
A ________ (pulse/wave) is a disturbance which is sudden and lasts for a short duration of time.
Q 25.
Fill in the blanks :
In a __________ wave the particles of the medium oscillate in a direction perpendicular to the direction in which the wave propagates.
Q 26.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 27.
Fill in the blanks :
The distance between two consecutive compressions or two consecutive rarefactions is called the ______________.
Q 28.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 29.
What is a mechanical wave?
Q 30.
What type of waves can travel in vacuum? Give example(s).
Q 31.
A sound wave travels at a speed of 339 ms
–1. If its wavelength is 1.5 cm, what is the frequency of the wave?
Q 32.
A hospital uses an ultrasonic scanner to locate tumors in a tissue. What is the wavelength of sound in a tissue is which the speed of sound is 1.7 km/s. The operating frequency of the scanner is 4.2 MHz. (1MHz = 10
6 Hz).
Q 33.
A boat anchor is rocked by waves whose consecutive crests are 100 m apart.If the wave speed of the moving crests is 20 m/s,calculate the frequency at which the boat rocks.
Q 34.
What are wavelength,frequency,time period and amplitude of a sound wave ?
Q 35.
What is sound barrier ?
Q 36.
What is persistence of hearing ?
Q 37.
What is the minimum distance of the obstacle from the source of sound for hearing distinct echo ?
Q 38.
There are no echoes produced in small living rooms.Explain why echoes are produced only in large galleries and halls.
Q 39.
What are transverse waves ?
Q 40.
Discuss the structure of human ear from auditory aspect only.
Q 41.
We see flash earlier than the thunder.Discuss.
Q 42.
Fill in the blanks :
If a body repeats its motion, within fix interval of time, along a certain path, about a fixed point, it is said to have ____________.
Q 43.
Fill in the blanks :
A ________ (pulse/wave) is a form of disturbance which travels through a medium as a result of repetitive oscillations of the particles of the medium.
Q 44.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 45.
Three persons, A, B and C are made to hear a sound travelling through different mediums as given below:
| Persons | Medium |
| A | Iron Rod |
| B | Air |
| C | Water |
Who will hear the sound first? Why?
Q 46.
What is a wave number?
Q 47.
How are the wavelength and frequency of a sound wave related to its speed?
Q 48.
Which wave characteristics determine the
(a) Loudness (b) pitch of sound?
Draw two different waveforms and mark these characteristics on it.
Q 49.
A hospital uses an ultrasonic scanner to locate tumours in a tissue.What is the wavelength of sound in a tissue in which the speed of sound is 1.7 km/s ? The operating frequency of the scanner is 4.2 MHz.
Q 50.
What is sound and how is it produced ?
