Answer:

Explanation:
From the question we are told that
Weight 
Altitude 
Speed 
Generally the equation for Potential energy ids mathematically given as




Explanation:
Principle focus is the point on the axis of a convex lens, where the parallel rays of light from one side of the lens. meet on other side after refraction. Distance between optical centre to principle focus point is the focal length.
Answer:
You would have to find the friction force of the rubber block which would be found with the equation of Normal force (mass*gravity) times cooeficient of friction which would give 8.82 N for the amount of friction and because you need more force than 8.82 N (assuming gravity is 9.8)