Answer: drying towels at the beach.
Explanation:
Radiation simply has to do with the energy that is gotten from a particular source and then goes through some materials. It simply means the way energy is being transmitted as waves or heat through a certain medium.
From the options given, the scenario whereby a radiation takes place is when drying towels on the beach.
Image formed by a plane mirror is always virtual which means that the light rays do not actually come from the image but upright and these of the same shape and size are the object it is<span> reflecting.</span>
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.
