Lecture 13 - Ground Reaction Force Flashcards
What is friction?
Friction is a force that develops between two surfaces, preventing them from slipping past each other.
How does friction allow movement or acceleration of the body?
Friction allows the ground to exert a significant enough force on the foot to accelerate the body, as it acts against the direction of slipping.
What is the formula for calculating the force of friction?
The force of friction can be calculated using the formula F=μR, where
F is the frictional force,
μ is the coefficient of friction, and
R is the normal force, which acts perpendicular to the surfaces in contact.
In which direction does friction act?
Friction acts in the direction opposite to the direction of motion or impending motion.
How does the magnitude of friction affect the motion between two objects?
The magnitude of friction determines how easy or difficult it is to create a sliding motion between two objects. Greater friction means increased difficulty for the objects to slip with respect to each other.
What happens to the difficulty of sliding motion between two objects if the friction between them is increased?
If the friction between two objects is increased, the difficulty of creating a sliding motion between them also increases.
Does the area of contact between two surfaces affect the frictional force between them?
No, the frictional force does not increase with greater surface area since the area isn’t part of the friction equation.
When is friction greatest
Friction is greatest at (C), just before the object moves
Static friction:
the friction between two surfaces when they are not moving
What is kinetic friction?
Kinetic friction, also known as dynamic friction, is the friction that occurs between surfaces in motion relative to each other.
How does the magnitude of kinetic friction change with the speed of the moving surfaces or the force applied to them?
The magnitude of kinetic friction remains constant, regardless of how fast the two surfaces are moving or how hard you push them against each other.
Under what condition will sliding between two surfaces come to a stop?
Sliding will continue to occur between the two surfaces until the applied force drops below the level of kinetic friction, causing them to slow down and eventually come to a stop.
How does the force of static friction compare to the force applied on an object before it starts moving?
The force of static friction is proportional to and equal to the applied force up until the point where movement begins.
Is the maximum static friction force greater or less than kinetic friction?
The maximum static friction force is greater than kinetic friction.
How does kinetic friction compare to maximum static friction?
Kinetic friction is constant and less than the maximum static friction.
This means that the applied force required to maintain motion is greater than the kinetic friction force but less than the maximum static friction.
Why is the frictional force during motion (kinetic friction) considered constant?
Kinetic friction is considered constant because its magnitude does not depend on the speed of the moving surfaces or the magnitude of the force applied to them; it remains consistent under constant conditions of movement.