The ground reaction force (GRF) is the force exerted by the ground on an object in contact with it.
It is the force that opposes the force of gravity and allows us to stand upright. The magnitude of the GRF is equal to the weight of the object. The direction of the GRF is perpendicular to the surface of the ground.
Ground Reaction Force When Walking
When you walk, one foot is always in contact with the ground. The force that your foot exerts on the ground is called the ground reaction force. This force is equal to your body weight.
The ground reaction force acts in the opposite direction of your body’s motion. It is this force that propels you forward when you walk. The faster you walk, the greater the ground reaction force will be.
The ground reaction force also helps to keep you upright. When you lean forward, the ground reaction force pushes back against your body, keeping you from falling over.
Ground Reaction Force on Different Surfaces
The magnitude of the GRF depends on the surface on which the object is sitting:
A harder surface will result in a smaller GRF, while a softer surface will result in a larger GRF.
The direction of the GRF also depends on the surface:
For example, a slippery surface will cause the GRF to act in a direction opposite to the object’s weight, while a sticky surface will cause the GRF to act in the same direction as the object’s weight.