Conduct Activity 1 once again with a thick rubber band and then with a thin rubber band. Class 9

Conduct Activity 1 once again with a thick rubber band and then with a thin rubber band. Class 9

Question 1.

Conduct Activity 1 once again with a thick rubber band and then with a thin rubber band. Does the thin rubber band vibrate faster than the thick rubber band? If yes, how do the frequency and time period of the sound produced by the thin rubber band differ from that of the thick rubber band? (Page 195) Class 9

Answer:

Yes, the thin rubber band vibrates faster than the thick rubber band. Since frequency is higher when vibrations are faster:

1. The frequency of the sound produced by the thin rubber band is higher than that of the thick rubber band.
2. The time period of the thin rubber band's sound is shorter (since T = 1/v, and frequency is higher, time period is smaller).

Question 2.

If the frequency of a sound wave produced by an oscillating piston of a long tube filled with air is 20 Hz, then how many oscillations does the piston complete per minute? (Page 195) Class 9

Answer:

Frequency = 20 Hz means 20 oscillations per second.

Oscillations per minute = 20 × 60 = 1200 oscillations per minute