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
Answer:
1.28 m
Explanation:
Generally, pressure of fluid is given by
where g is acceleration due to gravity, h is the height and 
is the density
Considering that the pressure for mercury is same as for blood only that the height and density of fluid are different then
Since g is constant, then
Making 
the subject of the formula then
Where subscripts m and b denote mercury and blood respectively
Assuming density of blood is 1060 Kg/m3, density of mercury as 13600 Kg/m3 and substituting height of mercury for 0.1 m then
Answer:
37.545 m/s
Explanation:
f' = Actual frequency of horn = 269 Hz
f = Observed frequency of horn = 290 Hz
v = Speed of sound in air = 343 m/s
= Speed of second train = 13.7 m/s
= Speed of first train
From Doppler effect we have
The speed of the first train is 37.545 m/s
Answer:
13.91 m/s
Explanation:
First we need to find the acceleration:
Acceleration = Force/mass
Acceleration = 36.7N/7.41 kg
Acceleration = 4.95 m/s² (rounded to two decimal places)
Then we find the velocity:
Velocity = Acceleration * Time
Velocity = 4.95 m/s² * 2.81 s
Velocity = 13.91 m/s (rounded to two decimal places)
