Question

When a body of mass 25Kg is suspended from a sonometer
wire then it vibrates with frequency 200 Hz. If the volume
of the body is 0.009 m and it is immersed in water then the
frequency of vibration of the wire will be​

Answer 1

Answer:

Fundamental Frequency in such a string is directly proportional to square root of tension.

ν

fundamental

=k

T

ν

fundamental

=c

m

(c is constant of different value, we take out g from tension, T = mg)

i.e.

50.7

260

=constant

Now the block is 0.0075 m

3

, by Archimedes principle we know that an upward buoyant force of ρVg=1000×0.0075×g=7.5g acts. This is equivalent to the block losing 7.5 kg in mass. i.e=50.7−7.5=43.2

Substituting this.

50.7

260

=

43.2

ν

Solving this we get ν=240 Hz ,which is the new fundamental frequency.