<h2>
Answer:</h2><h2>
It is due to a refractment of light.</h2>
Sound moves faster in warmer air than colder air the way bends away from the warm air and back towards of air.
To find the ratio of planetary speeds Va/Vb we need the orbital velocity formula:
V=√({G*M}/R), where G is the gravitational constant, M is the mass of the distant star and R is the distance of the planet from the star it is orbiting.
So Va/Vb=[√( {G*M}/Ra) ] / [√( {G*M}/Rb) ], in our case Ra = 7.8*Rb
Va/Vb=[ √( {G*M}/{7.8*Rb} ) ] / [√( {G*M}/Rb )], we put everything under one square root by the rule: (√a) / (√b) = √(a/b)
Va/Vb=√ [ { (G*M)/(7.8*Rb) } / { (G*M)/(Rb) } ], when we cancel out G, M and Rb we get:
Va/Vb=√(1/7.8)/(1/1)=√(1/7.8)=0.358 so the ratio of Va/Vb = 0.358.
Answer:
(a) 
(b) 
(c) 
Explanation:
(a) The orbital period is the time that the electron spend to travel the orbit of the atom. Thus, it is given by the length of the circular orbit divided by its velocity:

(b) Current means charge over time, So, in this case is charge over period:

(c) Magnetic moment is given by:

Here A is the area of the orbit.

(a) The work done by the gas during the isothermal expansion is -25.6 J.
(b) The heat added to the gas during this process is 25.6 J.
<h3>
Net work done by the ideal gas against the external pressure</h3>
The net work done by the ideal gas in the isothermal expansion is calculated as follows;
W(net) = ΔP x ΔV
W(net) = ( 1 kPa - 5 kPa) x (8L - 1.6 L)
W(net) = -25.6 kPa.L
W(net) = -25.6 J
<h3>Head added to the gas</h3>
The heat added to the gas is calculated as follows;
W = -Q
-25.6 J = -Q
Q = 25.6 J
Learn more about Isothermal expansion here: brainly.com/question/17192821
Because the net force must be zero, we conclude that the magnitude of the force is 1500 newtons, and the direction is in the positive axis.
<h3>
What is the magnitude and direction of the third force?</h3>
By Newton's laws, we know that if the net force applied to an object is different than zero, then the object is accelerated.
In this case, we know that the object moves with constant velocity, so there is no acceleration, meaning that the net force is equal to zero.
Then we must have:
F1 + F2 + F3 = 0N
Replacing F1 and F2 we get:
-3000 N + 1500N + F3 = 0
F3 = 3000N - 1500 N = 1500N
Then the magnitude of the force is 1500 newtons, and the direction is in the positive axis.
If you want to learn more about Newton's laws, you can read:
brainly.com/question/10454047