The average power is 10 watts. What's the question ?
Total internal reflection causes light to be completely reflected across the boundary between the two media but not transmitted.
<h3>What is total internal reflection?</h3>
The term total internal reflection occurs when light is moving from a denser to a less dense medium such as from glass to air. This phenomenon occurs at the interface between the two media.
There are two conditions necessary for total internal reflection and they are;
1) Light must travel from a denser to a less dense medium
2) The angle of incidence in the denser medium must be greater than the critical angle.
Total internal reflection causes light to be completely reflected across the boundary between the two media but not transmitted.
Learn more about total internal reflection:brainly.com/question/13088998
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Considering that the book is moving with constant speed, the force applied by Anna must be the same that the friction force:

If we clear the previous equation:
Answer:
c. As we gain mass, the force of gravity on us increases
We know, Potential Energy = m * g * h
Here, mass & gravity would be same, but their height will change so it will be:
ΔU = U₂ - U₁
ΔU = mgh₂ - mgh₁
ΔU = mg (h₂ - h₁)
Hope this helps!