Answer:
Step-by-step explanation:
The problem is based on vibration in string .For it the formula is as follows :
n = k √T , n is frequency of fundamental tone , k is constant for a string of given length and T is tension in the string .
In the first case weight of sphere is equal to tension .
weight = volume of sphere x density of copper x g
= v x 8960 x g
Putting the values
300 = k √ (v x 8960 x g)
300 = k √ 87808v
When the sphere is half submerged
tension is equal to apparent weight of sphere in water
= v x 8960 x g - .5 v x 1000 x 9.8 , v is volume
= 82908v
for second case
n = k √ 82908v
dividing the two equations
n / 300 =

= .9716
n = 291.5 Hz .