Question is how high he could actually leap then. His range was 660 feet, what he would need in velocity to make that height to jump off from the sidewalk to get to that max height. With his final velocity, at 660 feet,which will be 0. Meaning his initial velocity would be 140 miles per hour is what will determine his highest point. Superman also weighs 220 pounds and his mass is 100 kilograms. The force of gravity remains constant through the entire event. With his initial speed, the force of gravity, and the max height that he can leap, how do you explain how he can reach that velocity in a leap?
Thou he crouches and pushes back on the ground, he is still effected by the force of gravity along with his mass and acceleration. This is where you take in the account that he is not earth born, but from the planet Krypton, where the gravity is much stronger. Superman's DNA made his muscles and body to survive the force of gravity on Krypton his home planet, so just much stronger is the force of gravity on Krypton?
The Physics of Superheroes by James Kakalios
Chapter 1, pages 21 - 32
Published by "Gotham Books"
Kakalios, James. The Physics of Superheroes. New York: Gotham, 2005. Print.