Answer: B. 4
Step-by-step explanation:
First, I did the equation out.
Second, I simply it all the way through.
Third, to get 4
Answer:
correct option is C) 2.8
Step-by-step explanation:
given data
string vibrates form = 8 loops
in water loop formed = 10 loops
solution
we consider mass of stone = m
string length = l
frequency of tuning = f
volume = v
density of stone =
case (1)
when 8 loop form with 2 adjacent node is
so here
..............1

and we know velocity is express as
velocity = frequency × wavelength .....................2
= f ×
here tension = mg
so
= f ×
..........................3
and
case (2)
when 8 loop form with 2 adjacent node is
..............4

when block is immersed
equilibrium eq will be
Tenion + force of buoyancy = mg
T + v ×
× g = mg
and
T = v ×
- v ×
× g
from equation 2
f ×
= f ×
.......................5
now we divide eq 5 by the eq 3

solve irt we get

so
relative density 
relative density = 2.78 ≈ 2.8
so correct option is C) 2.8
The first x is the horizontal coodinate (abscisa) and second is the vertical coordinate (ordenate). Both are coordinates. (x,y) has the meaning of a complex number: x is the real part and y is the imaginary part: x+yi. (x,y) has the meaning of a plane's vector from origin of coordinates.