Answer:
Thermal Power = 460W
Explanation:
From Stephan-Boltzmann Law Formula;
P = єσT⁴A
Where,
P = Radiation energy
σ = Stefan-Boltzmann Constant
T = absolute temperature in Kelvin
є = Emissivity of the material.
A=Area of the emitting body
Now, σ = 5.67 x 10^(-8)
є = 0.6
Temperature = 30°C and coverting to kelvin = 30 + 273 = 303K
Area ; since we are to consider the sides of the human body as 2m and 0.8m,thus area = 2 x 0.8 = 1.6
Thus thermal power = 0.6 x 5.67 x 10^(-8) x303⁴ x 1.6 = 458. 8W
Normally, we approximate to the nearest 10W. Thus, thermal power is approximately 460W
At the rear.
PWC stands for personal watercraft, and it is a small powerboat. The main components of a PWC are the hull (body of the boat), deck (surface where people walk/stand), throttle (controls speed), steering nozzle and water intake.
The correct answer is Option C) Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.
As the coefficient of absorption would define the energy present in the reflected wave, the material C has the highest percentage of absorption i.e. 62% and would be best suitable to make a sound proof room.
Answer:
a) L = 0.75m f₁ = 113.33 Hz
, f₃ = 340 Hz, b) L=1.50m f₁ = 56.67 Hz
, f₃ = 170 Hz
Explanation:
This resonant system can be simulated by a system with a closed end, the tile wall and an open end where it is being sung
In this configuration we have a node at the closed end and a belly at the open end whereby the wavelength
With 1 node λ₁ = 4 L
With 2 nodes λ₂ = 4L / 3
With 3 nodes λ₃ = 4L / 5
The general term would be λ_n= 4L / n n = 1, 3, 5, ((2n + 1)
The speed of sound is
v = λ f
f = v / λ
f = v n / 4L
Let's consider each length independently
L = 0.75 m
f₁ = 340 1/4 0.75 = 113.33 n
f₁ = 113.33 Hz
f₃ = 113.33 3
f₃ = 340 Hz
L = 1.5 m
f₁ = 340 n / 4 1.5 = 56.67 n
f₁ = 56.67 Hz
f₃ = 56.67 3
f₃ = 170 Hz
