(a) Sound cannot travel in vacuum. (True)
(b) The number of oscillations per second of a vibrating object is called its time period. (False)
(c) If the amplitude of vibration is large, sound is feeble. (False)
(d) For human ears, the audible range is 20 Hz to 20,000 Hz. (True)
(e) The lower the frequency of vibration, the higher is the pitch. (False)
(f) Unwanted or unpleasant sound is termed as music. (False)
(g) Noise pollution may cause partial hearing impairment. (True)
Fill in the blanks in the sentences below (the verbs given in brackets will give you a clue).
(i) The earth trembled, but not many people felt the ____. (tremble)
(ii) When the zoo was flooded, there was a lot of _____ and many animals escaped into the countryside. (confuse)
(iii) We heard with _____ that the lion had been recaptured. (relieve)
(iv) The zookeeper was stuck in a tree and his _____ was filmed by the TV crew. (rescue)
(v) There was much _____ in the village when the snake charmer came visiting. (excite)
First monomial → Second monomial ↓ | 2x | –5y | 3x2 | – 4xy | 7x 2 y | –9x 2 y 2 |
2x | 4x2 | . . . | . . . | . . . | . . . | . . . |
–5y | . . . | . . . | -15x2y | . . . | . . . | . . . |
3x2 | . . . | . . . | . . . | . . . | . . . | . . . |
– 4xy | . . . | . . . | . . . | . . . | . . . | . . . |
7x 2 y | . . . | . . . | . . . | . . . | . . . | . . . |
–9x2 y2 | . . . | . . . | . . . | . . . | . . . | . . . |
Sound is a vibration that propagates the mechanical wave of displacement and pressure, through a medium can be of any matter. In other words, the sound is the thin line between Music sound and Noise.
Sound can be divided into two types depending on its frequency. The following are:-