friction
The force that one surface exerts on another surface when the surfaces come into contact with each another.
Friction
The state in which one object's distance from another object is getting closer or further apart. Described as distance, displacement, velocity, speed, acceleration, etc.
Motion
The ability to do work or cause change.
Energy
A place or object used for comparison to determine if an object is in motion.
Reference Point
A particle attracts every other particle in the universe using a force. The greater the mass, the greater the attraction. The greater the distance, the weaker the attraction.
Newton's Law of Universal Gravitation
Occurs when two objects slide over each other. Example: sand on an icy sidewalk to improve footing, rubber brake pads rubbing on tire rim to slow a bike.
sliding friction
The overall rate of speed at which an object travels or moves; calculated by dividing the total distance an object travels by the total time.
Average Speed
A push or a pull exerted on an object. It is described by its strength and direction in which it acts.
Force
The basic SI unit for length.
Meter (m)
Developed laws of motion, theory of gravity and believed that comets sustained life on earth and other planets.
Sir Isaac Newton (1642-1727)
When a body moves in a fluid or in air then there exists a resistive force which slows down the motion of the body. A freely falling skydiver feels a drag force due to air which acts in the upward direction or in a direction opposite to skydiver's motion.
fluid friction
Speed in a given direction (speed with a direction).
Velocity
Equal forces acting on an object in opposite directions (no motion).
Balanced Forces
The distance an object travels per unit of time.
Speed
An object at rest stays at rest and an object in motion stays in motion with the same velocity and in the same direction unless acted upon by an unbalanced force.
Newton's First Law (Inertia)
Comes into play when a body is forced to move along a surface but movement does not start (no motion).
Static Friction
The speed of an object at one instant of time.
Instantaneous Speed
Forces that produce a nonzero net force, which changes and object's motion (motion).
Unbalanced Force
The greatest velocity a falling object can achieve.
Terminal Velocity
Explains behavior of an object. Acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. As the force acting upon an object is increased, the acceleration of the object is increased. As the mass of an object is increased, the acceleration of the object is decreased.
newtons second law
A force that slows down the motion of a rolling object. Basically, it is a combination of various types of frictional forces at point of contact of wheel and ground or surface. When soft object moves over a hard surface then its distortion makes it slow down.
Rolling Friction
Is when a moving object increases speed, decreases speed or changes direction.
Acceleration
The force that pulls all object towards each other. Example: The Earth's attraction to the sun.
gravity
In physics, this is the motion of a body moving through the atmosphere with gravity as the only force acting on the body.
free fall
For every action, there is an equal and opposite reaction.
Newton's Third Law