Kinetic Friction: Acts on moving surfaces, constant magnitude. | Static Friction: Acts on surfaces at rest, self-adjusting up to a maximum value.

Coefficient of Static Friction ($\mu_s$): Usually greater than $\mu_k$, represents the force needed to start motion. | Coefficient of Kinetic Friction ($\mu_k$): Usually smaller than $\mu_s$, represents the force needed to maintain motion.

At Rest: Static friction balances the component of gravity pulling the object down the plane. | Sliding: Kinetic friction opposes the motion down the plane, but the net force results in acceleration.

Kinetic Friction: $F_k = \mu_k N$ (always equal to this value when sliding) | Maximum Static Friction: $f_{s,max} = \mu_s N$ (static friction can be any value from zero up to $f_{s,max}$)

Kinetic Friction: Magnitude of kinetic friction force remains constant regardless of the contact area between the surfaces. | Static Friction: The area of contact does not affect the maximum static friction force.

A force that opposes the motion of surfaces sliding against each other.

A force that prevents surfaces from slipping when they are at rest relative to each other.

An empirical value that depends on the materials of the contacting surfaces, used to calculate kinetic friction.

An empirical value that depends on the materials of the contacting surfaces, used to calculate the maximum static friction force.

The force acting perpendicular to the surface of contact.

1: Identify the surfaces in contact. 2: Determine the normal force (N). 3: Find the coefficient of kinetic friction ($\mu_k$). 4: Calculate $F_k = \mu_k N$.

1: Calculate the maximum static friction force ($f_{s,max} = \mu_s N$). 2: Compare the applied force (F) to $f_{s,max}$. 3: If $F > f_{s,max}$, the object moves; otherwise, it remains at rest.

1: Identify the angle of the incline ($\theta$). 2: Calculate the normal force using $N = mg \cos\theta$, where m is the mass and g is the acceleration due to gravity.

1: An object slides across a surface. 2: Kinetic friction acts opposite to the motion, doing negative work. 3: This work converts kinetic energy into thermal energy, increasing the temperature of the surfaces.

1: Draw a free body diagram. 2: Calculate the normal force. 3: Calculate the kinetic friction force. 4: Determine the net force along the incline. 5: Use Newton's Second Law ($F_{net} = ma$) to find the acceleration.