Answer:
Explanation:
Gauss' Law should be applied to find the E-field 3.9 cm from the surface of the sphere.
In order to apply Gauss' Law, an imaginary spherical shell (Gaussian surface) should be placed around the original sphere. The exact position of the shell must be 3.9 cm from the surface of the original sphere.
Gauss' Law states that
Here, the integral in the left-hand side is equal to the area of the imaginary surface. After all, the reason behind choosing the imaginary surface a spherical shell is to avoid this integral. The enclosed charge in the right-hand side is equal to the charge of the sphere, -84.0 nC. The radius of the imaginary surface must be 5 + 3.9 = 8.9 cm.
So,
Because the light colors will only work on a dark background, as dark colors will only work on a light background. If light color were on the white background not only will it be nearly impossible to read, the letters with have to be much larger for older people to read or see. Therefore, Black letters on a white background is most common. But a Black background with white letters could also work, kind of like a chalkboard.
I think A, because rodents already live in winter months when little food is available, but I'm not sure.
<span>The maximum possible efficiency, i.e the efficiency of a Carnot engine , is give by the ratio of the absolute temperatures of hot and cold reservoir.
η_max = 1 - (T_c/T_h)
For this engine:
η_max = 1 - [ (20 +273)K/(600 + 273)K ] = 0.66 = 66%
The actual efficiency of the engine is 30%, i.e.
η = 0.3 ∙ 0.664 = 0.20 = 20 %
On the other hand thermal efficiency is defined as the ratio of work done to the amount of heat absorbed from hot reservoir:
η = W/Q_h
So the heat required from hot reservoir is:
Q_h = W/η = 1000J / 0.20 = 5000J</span>
0 Newtons, since it's at a constant speed. Hope this helps, and Brainliest answer would be appreciated!