When blocking in football, why does a defending lineman often attempt to get his body under that of his opponent and push upward? What effect does this have on the friction force between the opposing lineman's feet and the ground?
it reduces the friction which makes the lineman unstable.
This makes it easier for the defending lineman to move the opposing lineman out of the way. The reduced friction force between the feet and the ground also makes it easier for the defending lineman to maintain his balance and stay in position.
When a defending lineman attempts to get his body under that of his opponent and push upward in football, it is done for several reasons:
1. Leverage: By getting lower and pushing upward, the defending lineman can gain a mechanical advantage. This technique allows the lineman to apply more force against the offensive lineman and potentially drive him backward.
2. Control: By getting underneath the opponent and pushing upward, the defending lineman gains better control over the engagement. This allows the defender to dictate the direction of the play and prevent the offensive lineman from gaining ground.
Now, let's talk about the effect this technique has on the friction force between the opposing lineman's feet and the ground. Contrary to the idea that this reduces friction, pushing upward actually increases the friction force between the opposing lineman's feet and the ground.
When the defending lineman applies force upward, it counters the downward force applied by the offensive lineman. This results in an increased normal force acting on the feet of the offensive lineman. According to the laws of friction, the friction force between two surfaces is directly proportional to the normal force between them. So, with an increased normal force due to the defending lineman pushing upward, the friction force between the offensive lineman's feet and the ground also increases.
By increasing the friction force, the defending lineman makes it more difficult for the offensive lineman to move and maintain stability. This makes it harder for the offensive lineman to generate power and effectively execute blocking techniques, ultimately giving the defending lineman an advantage in the play.
When a defending lineman tries to get his body under his opponent and push upward, it serves multiple purposes. First, by getting low and pushing upward, the defender can leverage his own strength against the opposing lineman's center of gravity, making it harder for the offensive lineman to drive through or push the defender backward. This technique is commonly known as a "low pad level" or a "bull rush."
Now, let's look at the effect this has on the friction force between the opposing lineman's feet and the ground. When the defender pushes upward, it actually increases the friction force between the offensive lineman's feet and the ground. Friction is the force that opposes relative motion between two surfaces in contact, and it acts parallel to the surface in contact. By pushing upward with force, the defender increases the normal force (the force exerted perpendicular to the surface) between the offensive lineman's feet and the ground, which in turn increases the friction force.
So, to correct your initial statement, when a defending lineman tries to get his body under his opponent and push upward, it does not reduce the friction force. Instead, it increases the friction force, making it more difficult for the opposing lineman to maintain stability and move effectively.