<h2>
Answer: 0.17</h2>
Explanation:
The Stefan-Boltzmann law establishes that a black body (an ideal body that absorbs or emits all the radiation that incides on it) "emits thermal radiation with a total hemispheric emissive power proportional to the fourth power of its temperature":
(1)
Where:
is the energy radiated by a blackbody radiator per second, per unit area (in Watts). Knowing 
is the Stefan-Boltzmann's constant.
is the Surface area of the body
is the effective temperature of the body (its surface absolute temperature) in Kelvin.
However, there is no ideal black body (ideal radiator) although the radiation of stars like our Sun is quite close. So, in the case of this body, we will use the Stefan-Boltzmann law for real radiator bodies:
(2)
Where 
is the body's emissivity
(the value we want to find)
Isolating from (2):
(3)
Solving:
(4)
Finally:
(5) This is the body's emissivity
Answer:
Your answer is given below:
Explanation:
Answer:
It's probably the Redshift and Blueshift
Explanation:
The light shifting towards shorter or longer wavelengths as objects in space (stars or galaxies) move closer or farther away from us. This phenomenon is known as the Redshifts and Blueshifts. The concept indicates us that the Universe is expanding.
Hope this helps you!
Bye!
Answer:
V= 33.98 m/s
Explanation:
Given that
Horizontal speed ,u= 17 m/s
Time taken by rockets to strike the water ,t= 3 s
We know that acceleration due to gravity ,g= 9.81 m/s²
There is no any acceleration in the horizontal direction that is why the horizontal veloity will remain constant.
In the vertical direction
vy = uy+ g t
Initial velocity in vertical direction is 0 m/s.
vy= 0+ 9.81 x 3
vy = 29.43 m/s
The resultant velocity
V= 33.98 m/s
