At the peak of its flight ALL the energy given to the rocket is potential energy (its velocity is zero) and that is calculated as mgh So Energy given to rocket = mgh Energy expended by engine = F x D (D= height where engine stops) Energy 'lost' to drag is the difference between the two values. please if this helped mark it as the brainiest answer.
I think it's b..................
Answer:

Explanation:
Given:
height above which the rock is thrown up, 
initial velocity of projection, 
let the gravity on the other planet be g'
The time taken by the rock to reach the top height on the exoplanet:
where:
final velocity at the top height = 0 
(-ve sign to indicate that acceleration acts opposite to the velocity)

The time taken by the rock to reach the top height on the earth:



Height reached by the rock above the point of throwing on the exoplanet:

where:
final velocity at the top height = 0 


Height reached by the rock above the point of throwing on the earth:



The time taken by the rock to fall from the highest point to the ground on the exoplanet:
(during falling it falls below the cliff)
here:
initial velocity= 0 



Similarly on earth:

Now the required time difference:


Answer:
entertaining form of repetition
Explanation:
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