Answer:
The potential energy has a maximum when the ball is a time that is half of the time for total travel
Explanation:
Generally potential energy is a the varies directly with the height according to this formula

and the ball attains a maximum height when the time is equal to half of the total time taken to travel
Should be 250m. check with your teacher and let me know
Answer:
work output is always less than work input - the ratio is less than 1.
Explanation:
This principle comes from the fact that a machine or system cannot produce more work than is supplied to it, because this would violate the energy conservation law (work is a type of mechanical energy).
In theoretical machines called "ideal machines" the input work is the same as the output work, but these machines are only theoretical because in real applications there is always some type of energy loss, either in heat produced by a machine or processes for its operation, for this reason the output work is always less than the input work.
Regarding the ratio work output to work input:

because work input WI is always greater than work output WO.
Any two objects in the universe attract each other. Gravity is the force exerted by earth on you (you exert the same force on earth) but due to the fact that earth has a huge mass compared to yours, you will be attracted to earth only by a small gravitational force.
They need more oxygen to function, so gas exchange needs to increase