Model Test Paper മാതൃകാ ചോദ്യപേപ്പർ
A full paper in the Kerala Class 9 Physics pattern, covering the whole of “Sound” – how sound is produced, musical instruments and our voice, the need for a medium, the speed of sound (Table 8.3), the ear and hearing, hearing impairment, music and noise, and noise pollution. Most questions are conceptual; a few numericals use distance = speed × time. Work on paper with a timer before you look at the solutions.
Standard IX · Physics
Chapter 8 · ശബ്ദം · Sound
- The first 15 minutes are cool-off time: read every question and plan your answers; do not write.
- Answer all questions. Marks for each question are shown on the right.
- For numericals write Given → Formula → Substitution → Answer with the unit.
- Use the speeds of sound given in the question (Table 8.3 values); speed of light = 3 × 108 m/s.
SECTION AAnswer all · 8 × 1 = 8 marks
1.
Sound is produced by the of objects.
(1)2.
Sound cannot travel through
(1)(a) steel(b) water(c) air(d) vacuum
3.
From Table 8.3, sound travels fastest in
(1)(a) air(b) sea water(c) helium(d) aluminium
4.
Find the relation and fill in: tabla : stretched skin (membrane) :: odakkuzhal (flute) :
(1)5.
When we speak, the in the larynx (voice box) vibrate.
(1)6.
The thin membrane in our ear that vibrates when sound reaches it is the
(1)(a) outer ear (pinna)(b) ear canal(c) eardrum(d) inner ear
7.
Pick the odd one out and give the reason: chenda, mridangam, veena, tabla.
(1)8.
The sound engineer from Anchal, Kollam, who won the Oscar for sound mixing for the film Slumdog Millionaire is .
(1)SECTION BAnswer all · 5 × 2 = 10 marks
9.
At night Arun sees the flash of a firecracker and hears its sound 4 s later. How far away did it burst? (Take the speed of sound in air as 350 m/s.)
(2)10.
Astronauts standing on the Moon cannot hear each other speak directly, even when they stand close together. (a) Why? (b) How do they talk to each other?
(2)11.
Music and noise are both sounds. (a) What is the difference between them? (b) Give one example of each.
(2)12.
Lightning and thunder happen at the same moment, but we usually see the lightning first and hear the thunder later. Why?
(2)13.
Write two difficulties faced by people with hearing loss, and two ways in which we can support them.
(2)SECTION CAnswer all · 4 × 3 = 12 marks
14.
An electric bell is ringing inside a glass bell jar placed on a vacuum pump (figure). The pump slowly removes the air from the jar. (a) What happens to the sound we hear? (b) When almost all the air has been removed, can we still see the hammer striking the gong? Can we hear it? (c) What do you conclude?
(3)15.
Complete the table.
(3)| Instrument | Main vibrating part | One associated part that vibrates |
|---|---|---|
| Violin | (i) ………… | (ii) ………… |
| Elathalam | (iii) ………… | (iv) ………… |
| Tabla | (v) ………… | (vi) ………… |
16.
A worker strikes one end of a long, empty steel pipeline with a hammer. Meera, 2972 m away at the other end, has her ear against the pipe. (Speed of sound: steel 5944 m/s, air 347 m/s – Table 8.3.) (a) How long does the sound take to reach her through the steel? (b) How long does it take through the air? (c) How many sounds does she hear? Which one comes first?
(3)17.
The figure shows how the sound of a tuning fork reaches our ear. (a) What do the letters C and R stand for? (b) Name the parts labelled 1, 2 and 3. (c) Name the three things needed for us to experience sound.
(3)SECTION DAnswer all · 2 × 5 = 10 marks
18.
During a monsoon storm Anu sees a flash of lightning and hears the thunder 6 s later. (Speed of sound in air 350 m/s; speed of light 3 × 108 m/s.) (a) Why does she hear the thunder after seeing the flash? (b) How far away did the lightning strike? (c) How long did the light of the flash take to reach her? (d) A few minutes later the gap is only 3 s. Is the storm coming nearer or moving away? Find its new distance. (e) Write two safety steps to take when thunder is heard.
(5)19.
“Noise pollution is a serious public-health problem.” (a) What is noise pollution? (b) Write two causes of noise pollution in our towns. (c) Write two harmful effects of noise on our health. (d) Name two groups of people who are affected the most. (e) Suggest two ways to reduce noise pollution.
(5)