Answer:
a. A uniform disk of radius and mass .
Explanation:
The moment of inertia I of an object depends on a chosen axis and the mass of the object. Given the axis through the point, the inertia will be drawn from the uniform disc having a radius and the mass.
.
Answer:
The wavelength of the wave is 20 m.
Explanation:
Given that,
Amplitude = 10 cm
Radial frequency 
Bulk modulus = 40 MPa
Density = 1000 kg/m³
We need to calculate the velocity of the wave in the medium
Using formula of velocity

Put the value into the formula


We need to calculate the wavelength
Using formula of wavelength


Put the value into the formula


Hence, The wavelength of the wave is 20 m.