a phenomenon about which competent observers who have made a series of observations are in agreement
An educated guess; a reasonable explanation of an observation or experimental result that is not fully accepted as factual until tested over and over again by experiment
A general hypothesis or statement about the relationship of natural quantities that has been tested over and over again and has not been contradicted. Also known as a principle
Fake science that pretends to be real science
Principles and procedures for the systematic pursuit of knowledge involving the recognition and formulation of a problem, the collection of data through observation and experiment, and the formulation and testing of hypotheses
A synthesis of a large body of information that encompasses well-tested and verified hypotheses about certain aspects of the natural world
Newton's first law of motion
Every object continues in its state of rest, or of uniform motion in a straight line, unless compelled to change that state by forces impressed upon it
The property of things to resist changes in motion
In the simplest sense, a push or a pull.
The vector sum of forces that act on an object
The state of an object or system of objects for which there are not changes in motion. In accord with Newton's first law, if at rest, the state of rest persists. If moving, motion continues without change.
For any object or system of objects in equilibrium, the sum of the forces acting equals zero.
How fast something moves; the distance traveled per unit of time.
The speed of an object and a specification of its direction of motion.
Quantity in physics that has both magnitude and direction
The rate at which velocity changes with time; the change in velocity may be in magnitude, or direction, or both.
Motion under the influence of gravity only
The resistive force that opposes the motion or attempted motion of an object either pass another object with which it is in contact or through a fluid.
The quantity of matter in an object. More specifically, it is the measure of the inertia or sluggishness that an object exhibits in response to any effort made to start, stop it, deflect it, or change in any way its state of motion.
The force due to gravity on an object
The fundamental SI unit of mass.
The SI unit of force.
The quantity of space an object occupies.
Newton's second law
The acceleration of an object is directly proportional to the net force acting on the object, is in direction of the net force, ans is inversely proportional to the mass of the object.
Any influence that can cause an object to be accelerated, measured in newtons.
Motion under the influence of gravitational pull only.
The speed at which the acceleration of a falling object terminates because air resistance balances its weight.
Newton's third law
Whenever one object exerts a force on a second object, the second objects exerts an equal and opposite force on the first.
A quantity that has both magnitude and direction.
A quantity that has magnitude but not direction.
An arrow drawn to scale used to represent a vector quantity
The net result of a combination of two or more vectors
The product of the mass of an object and its velocity
The product of the force acting on an object and the time during which it acts
Relationship of impulse and momentum
Impulse is equal to the change in the momentum of the object that the impulse acts upon.
Law of conservation of momentum
In the absence of an external force, the momentum of a system remains unchanged. Hence, the momentum before an event involving only internal forces is equal to the momentum after the event.
A collision in which colliding objects rebound without lasting deformation or the generation of heat.
A collision in which the colliding objects become distorted, generated heat, and possibly stick together.
The product of the force and the distance moved by the force
the time rate of work
The property of a system that enables it to do work
Energy due to the position of something or the movement of something
The energy that something possesses because of its position.
Energy of motion
The work done on an object equals the change in kinetic energy of the object
Conservation of energy
Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes.
A device, such as a lever or pulley, the increases (or decreases) a force or simply changes the direction of a force
Simple machine consisting of a rigid rod pivoted at a fixed point called a fulcrum
The percentage of the work put into a machine that is converted into useful work output.
The linear speed tangent to a curved path such as in circular motion.
The number of rotations or revolutions per unit of time; often measured in rotations or revolutions per second or per minute.
That property of an object that measures its resistance to any change in its state of rotation; if at rest, the body tends to remain at rest; if rotating, it tends to remain rotating and will continue to do so unless acted upon by an external net torque.
The product of force and lever-arm distance, which tends to produce rotation.
Center of mass
The average position of the mass of an object. The __ moves as if all the external forces acted at this point.
Center of gravity
The average position of weight or the single point associated with an object where the force of gravity can be considered to act.
The state of an object in which it is not acted upon by a net force or a net torque.
A force directed toward a fixed point, usually the cause of circular motion.
An outward force apparent in a rotating frame of reference. It is apparent (fictitious) in the sense that it is not part of an interaction but is a result of rotation- with no reaction-force counterpart.
The product of a body's rotational inertia and rotational velocity about a particular axis.
Conservation of angular momentum
When no external torque acts on an object or a system of objects, no change of angular momentum can occur. Hence, the angular momentum before an event involving only internal torques or no torques is equal to the angular momentum after the event.