Question

1. In which medium does sound travel the fastest?

a. salt water
b. fresh water
c. air
d. cast iron

2. A wave has a wavelength of 10 mm and a frequency of 5 hertz. What is its speed?
a. 50 mm/s
b. 50 hertz/s
c. 2 mm/s
d. 0.50 mm/s

3. How does reflection differ from refraction and diffraction?
a. Reflection is the only process in which the wave does not continue moving forward.
b. Reflection is the only process that involves a change in the wave.
c. Reflection affects all types of mechanical waves, but refraction and diffraction do not.

Answer 1

1- CAST IRON

2- 50 mm/s

3- Reflection is the only process in which the wave does not continue moving forward.

Answer 2

Answer : 1. cast iron

2. 50 mm/s

3. Reflection is the only process in which the wave does not continue moving forward.

Explanation :

1. The speed of sound is greatest in solid. So, the speed of the sound is fastest in cast iron. It is approximately equal to 4600 m/s.

2. Wavelength, λ = 10 mm

Frequency, υ = 5 Hz

Speed = wavelength × frequency

Speed = 10 mm × 5 s⁻¹

Speed, s = 50 mm/s

3. The bouncing back of light is called the reflection of light. In this process, the wave does not continue moving forward.