Final answer:
A football player can be more effective with his feet on the ground due to momentum, work, and energy. By using their feet as a strong base, players can transfer momentum and generate more power in blocking, hitting, and tackling. The leg muscles provide greater force and utilize stored energy for quicker and more powerful movements.
Step-by-step explanation:
A football player can be more effective with his feet on the ground in blocking, hitting, and tackling because of the concepts of momentum, work, and energy.
When a player plants his feet on the ground, he creates a strong base and increases his ability to transfer momentum to an opponent. By exerting force on the ground, the player can push against it and generate more power, resulting in a more effective block or tackle.
Additionally, having their feet on the ground allows players to use their leg muscles to generate greater force and take advantage of the energy stored in their muscles, making their movements quicker and more powerful.