Long Answer Question,
Q1: Explain the mechanism of hearing in human body.
Ans: Sound plays an important role in our life; Sound helps us to communicate with one another.Sound is so important because animals are able to hear events all around them, no matter where their attention is focused or not. The eardrum, or tympanic membrane, is a thin, cone-shaped membrane that separates the external ear from the middle ear in humans, it is like a stretched rubber sheet, sound vibrations make the eardrum vibrate. The ear drum sends vibration to the inner ear and from there signal is send to the brain and in this way we are able to hear the sounds around us.
Q2: “Sound travels through a medium, it cannot travel in vacuum”. Justify the statement.
Ans: Sound travels through a medium solid, liquid and gas. It cannot travel through vacuum.Fill a bucket with water and shake a bell under the water with one hand make sure that the bell should not touch the body of the bucket. Now place your ear gently on the water surface, you will hear the sound of the ringing bell, thus we can say that sound can travel through water.Take a metal rod and hold its one end to your ear, ask your friend to tap at the other end of metal rod you will hear the sound of tapping, thus this proves that sound can travels through solid.
Q3: A pendulum oscillates 50 times in 6 seconds. Find its time period and frequency.
Ans: Frequency of oscillation is defined as the number of oscillation of a vibrating body per second. it is given by
Frequency = no of oscillation/ time period = 50/6 = 8.33 Hz
Time period =1/frequency of oscillation = 1/ 8.33 = 0.12 seconds.
Q4: The sound from a butterfly is produced when it vibrates its wings at an average rate of 400 vibrations per second. What is the time period of vibration?
Ans: Time period =1/frequency of oscillation = 1/ 400 0.0025 seconds