Compute all parts of given question:
Question: An impala is an African antelope capable of a remarkable vertical leap. In one recorded leap, a 45 kg impala went into a deep crouch, pushed straight up for 0.21 s, and reached a height of 2.5 m above the ground.
Part I: To achieve this vertical leap, with what force did the impala push down on the ground?
Part II: What is the ratio of this force to the antelope's weight?
I need help to find with what force the impala pushed down on the ground.