Final answer:
In football, tackling with feet on the ground allows players to use their body mass and stability to generate greater force and momentum. This technique also enables a player to apply force over a longer distance, leading to more effective tackling through increased work and energy transfer. Padding provides the added benefit of reducing collision forces by increasing the time over which impacts occur, reducing the risks involved.
Step-by-step explanation:
Football coaches advise players to block, hit, and tackle with their feet on the ground because this technique makes use of the player's momentum, maximizes the application of work, and efficiently utilizes energy transfer. When a player's feet are planted on the ground, they can use the traction gained to push off the ground, thus applying a greater force over time, which in terms of physics, increases the impulse imparted to the opposing player. Additionally, having both feet on the ground provides more stability and allows for a controlled and directed application of force, which is crucial for effective tackling.
A football player's momentum is based on their mass and velocity. By staying connected to the ground, the player can engage more mass (due to gravity and their body weight) when applying force, which aids in momentum transfer. Furthermore, the concept of work comes into play—physics defines work as the product of force and the distance over which it is applied. A player who runs up to a tackle while grounded can apply force over a longer distance, doing more work and transferring more energy efficiently into their opponent.
Regarding impulse, which is the product of force and the time over which it is applied, padding helps reduce the force of collisions. For example, when a player wearing shoulder pads tackles another, the time over which the collision occurs is increased due to the cushioning effect of the pads, thus reducing the force experienced by both players, similar to the advantages of a carpeted floor in a daycare center in comparison to tile.