Sarcomere force vs. velocity with length and number

Question: Bill can lift exactly three times as much weight as everyone else in the school, even though he has the same amount of muscle. On the other hand, Jim can move his arm three times as fast but can barely lift a heavy book. You obtain muscle biopsies to analyze their muscle geometry.

If the length, number, cross section, and type of fibers the same in both, compare the relative sarcomere geometry (length and number) expected for each player. Discuss how their sarcomere geometry determines force and velocity.

I don't understand the answer provided for this question. That the length of each sarcomere for Bill is longer (more force) but this gives less velocity. The muscle fiber length and cross section is the same
in both, making sarcomeres bigger just increases the distance each one has to shorten to shorten the muscle a given distance. I don't understand how this affects force or speed. The answer is that Bill can generate 3x more force than everyone, but has 1/3 the velocity. Jim has 1/3 force but 3x the velocity. Explanations please?

Thank you!