Answer:
The efificiency is 0,25 of the machine (25%). See the explanation below
Explanation:
We calculate the efficiency with this formula:
Efficiency = energy obtained/energy supplied= 300 Joule/1200 Joule
Efficiency= 0,25
Efficiency(%) = 0,25 x100 = 25%
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:
The intensity I₂ of the light beam emerging from the second polarizer is zero.
Explanation:
Given:
Intensity of first polarizer = Io/2
For the second polarizer, the intensity is equal:

We use the kinematic equations,
(A)
(B)
Here, u is initial velocity, v is final velocity, a is acceleration and t is time.
Given,
,
and
.
Substituting these values in equation (B), we get
.
Therefore from equation (A),

Thus, the magnitude of the boat's final velocity is 10.84 m/s and the time taken by boat to travel the distance 280 m is 51.63 s