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
Since, the polygon is a trapezoid made up of a rectangle and a right triangle. Therefore, according to the question, the figure of the polygon is attached.
Since, perimeter is the total length of the outer boundary of the figure. Therefore,
Perimeter of the polygon is


Area of the polygon = Area of Rectangle + Area of Triangle
![=[(18) \times (15)] + [(\frac{1}{2}) \times (8) \times (15)]](https://tex.z-dn.net/?f=%3D%5B%2818%29%20%5Ctimes%20%2815%29%5D%20%2B%20%5B%28%5Cfrac%7B1%7D%7B2%7D%29%20%5Ctimes%20%288%29%20%5Ctimes%20%2815%29%5D)
![=270 + [(\frac{8}{2}) \times (15)]](https://tex.z-dn.net/?f=%3D270%20%2B%20%5B%28%5Cfrac%7B8%7D%7B2%7D%29%20%5Ctimes%20%2815%29%5D)
![=270 + [4 \times (15)]](https://tex.z-dn.net/?f=%3D270%20%2B%20%5B4%20%5Ctimes%20%2815%29%5D)


Answer:
see attachment
Step-by-step explanation:
The first number but it doesn't really matter.
Answer:
7.5 miles / hour
Step-by-step explanation:
See the step-by-step solution in the picture attached below.
I hope this answer will help you. Have a nice day !