Revision numericals

Sound – Numericals (MCQs)

1. A heart beats 75 times per minute. What is its frequency?

0.75 Hz 1.25 Hz 75 Hz 60 Hz

2. Time period of a pendulum is 2 s. Its frequency is

2 Hz 0.5 Hz 1 Hz 4 Hz

3. Separation between two crests is 100 m and velocity is 20 m s⁻¹. Frequency is

5 Hz 0.2 Hz 2 Hz 200 Hz

4. Velocity = 0.3 m s⁻¹, frequency = 20 Hz. Wavelength is

6 m 0.015 m 1.5 m 15 m

5. A source produces 40 crests and 40 troughs in 0.4 s. Frequency is

10 Hz 100 Hz 160 Hz 40 Hz

6. A gun is fired. Sound is heard 5 s later. Distance is 1650 m. Speed of sound is

300 m s⁻¹ 330 m s⁻¹ 350 m s⁻¹ 1650 m s⁻¹

7. Thunder is heard 5 s after lightning. Speed = 330 m s⁻¹. Distance is

660 m 1650 m 330 m 500 m

8. Sound is heard 2.5 s after seeing flash. Speed = 340 m s⁻¹. Distance is

425 m 850 m 680 m 340 m

9. Two tank sounds are heard 2 s and 3.5 s after flashes. Distance = 510 m. Speed is

300 m s⁻¹ 340 m s⁻¹ 170 m s⁻¹ 510 m s⁻¹

10. Time taken by sound to travel 3.3 km in air (speed 330 m s⁻¹) is

1 s 10 s 100 s 0.1 s

11. Time taken by sound to travel 1700 m in water (speed 1360 m s⁻¹) is

5 s 1.25 s 0.5 s 2 s