Glossary
Centripetal Force
A force that acts on an object moving in a circular path and is directed towards the center of the circle, causing the object to accelerate towards the center.
Example:
When a car rounds a curve, the centripetal force required to keep it on the circular path is often provided by static friction between the tires and the road.
Coefficient of Kinetic Friction (μk)
A dimensionless constant that represents the ratio of the kinetic friction force to the normal force between two surfaces that are sliding relative to each other.
Example:
A low coefficient of kinetic friction for waxed skis allows a skier to glide smoothly over snow.
Coefficient of Kinetic Friction (μk)
A unitless empirical value that quantifies the resistance to motion when two surfaces are sliding against each other.
Example:
The low coefficient of kinetic friction between ice skates and ice allows for smooth gliding.
Coefficient of Static Friction (μs)
A dimensionless constant that represents the ratio of the maximum static friction force to the normal force between two surfaces that are at rest relative to each other.
Example:
The high coefficient of static friction between rubber tires and asphalt is why cars can accelerate quickly without spinning their wheels.
Coefficient of Static Friction (μs)
A unitless empirical value that quantifies the maximum resistance to motion before two surfaces begin to slide relative to each other.
Example:
A high coefficient of static friction between climbing shoes and rock helps a climber maintain their grip.
Free Body Diagram
A visual representation used to analyze forces acting on an object, showing all forces as vectors originating from the object's center of mass.
Example:
Before solving a problem involving a block on an incline, drawing a free body diagram helps identify the normal force, gravitational force, and friction.
Friction
A force that opposes relative motion or the tendency of relative motion between two surfaces in contact.
Example:
When you walk, friction between your shoes and the ground allows you to push off and move forward without slipping.
Friction
A contact force that opposes motion or the tendency of motion between surfaces in contact.
Example:
When you try to push a heavy box across the floor, friction resists your effort.
Inclined Plane
A flat, sloped surface that allows an object to be moved from a lower to a higher elevation with less force than lifting it vertically.
Example:
Analyzing a sled sliding down a snowy hill involves understanding forces on an inclined plane, including friction and gravity components.
Kinetic Friction
The force that resists the motion of two surfaces sliding against each other, acting in the opposite direction of the relative motion.
Example:
The resistance a hockey puck experiences as it slides across the ice is due to kinetic friction.
Kinetic Friction
The force that opposes the relative sliding motion between two surfaces that are already in motion.
Example:
A snowboarder gliding down a slope experiences kinetic friction between the board and the snow, slowing them down.
Maximum Static Friction
The greatest amount of static friction that can be exerted between two surfaces before they begin to slide relative to each other.
Example:
To start pushing a heavy refrigerator, you must apply a force greater than the maximum static friction between its feet and the floor.
Newton's Second Law
States that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F_net = ma).
Example:
To calculate the acceleration of a box being pushed across a floor, you would apply Newton's Second Law by summing all forces and dividing by the mass.
Normal Force
The component of a contact force perpendicular to the surface that an object rests on or is in contact with, preventing the object from passing through the surface.
Example:
When a book rests on a table, the table exerts an upward normal force on the book, balancing its weight.
Normal Force (N)
The component of a contact force perpendicular to the surface that an object rests on or interacts with.
Example:
When a car is parked on a flat road, the road exerts an upward normal force on the car, balancing its weight.
Static Friction
The force that opposes the initiation of relative motion between two surfaces in contact, adjusting its magnitude up to a maximum limit.
Example:
A car parked on a hill is held in place by static friction between its tires and the road.
Static Friction
The force that prevents two surfaces from sliding relative to each other when they are at rest. It adjusts its magnitude up to a maximum limit.
Example:
A book resting on a tilted table is held in place by static friction until the angle becomes too steep.
Work-Energy Theorem
States that the net work done on an object is equal to the change in its kinetic energy.
Example:
When a car brakes, the negative work done by friction on the tires equals the reduction in the car's kinetic energy, as described by the Work-Energy Theorem.