Answer:
Minimum diameter=1.714
Explanation:
Angular magnification=fob/fey=42
fob=40*fey
Hence minimum diameter=diameter of objective/angular magnification
minimum diameter=72/42=1.714
Answer:12.8 ft/s
Explanation:
Given
Speed of hoop 
height of top 
Initial energy at bottom is

Where m=mass of hoop
I=moment of inertia of hoop
=angular velocity
for pure rolling 



Energy required to reach at top


Thus 512.2 m is converted energy is spent to raise the potential energy of hoop and remaining is in the form of kinetic and rotational energy

Therefore



Answer:
i believe its 26.7
Explanation:
if the runner goes 8.9 m/s each second while accelerating for 3 seconds to reach top speed, the top speed would be 26.7 m/s