All Physics Semester 1 Vocab

Science

The collective findings of humans about nature, and the process of gathering and organizing knowledge about nature.

Scientific method

An orderly method for gaining, organizing, and applying new knowledge.

Hypothesis

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.

Scientific attitude

The scientific method inclined toward inquiry, integrity, and humility.

Fact

A statement about the world that competent observers who have made a series of observations agree on.

Law

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.

Theory

A synthesis of a large body of information that encompasses well-tested and verified hypotheses about certain aspects of the natural world.

Pseudoscience

Fake science that pretends to be real science.

Technology

The means of solving practical problems by applying the findings of science.

Inertia

The property of things to resist changes in motion.

Newton’s first law of motion (the law of inertia)

Every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero net force.

Net force

The vector sum of forces that act on an object.

Vector

An arrow drawn to scale used to represent a vector quantity.

Vector quantity

A quantity that has both magnitude and direction, such as force.

Scalar quantity

A quantity that has magnitude but not direction, such as mass and volume.

Resultant

The net result of a combination of two or more vectors.

Mechanical equilibrium

The state of an object or system of objects for which there are no changes in motion. In accord with Newton’s first law, if an object is at rest, the state of rest persists. If an object is moving, its motion continues without change.

Equilibrium rule

For any object or system of objects in equilibrium, the sum of the forces acting equals zero. In equation form, (see book for equation, p.38) Sigma F = 0

Speed

How fast an object moves; the distance traveled per unit of time.

Instantaneous speed

The speed at any instant.

Average speed

The total distance traveled divided by the time of travel.

Velocity

An object’s speed and direction of motion.

Acceleration

The rate at which velocity changes with time; the change in velocity may be in magnitude, or direction, or both.

Force

Any push or pull exerted on an object, measured in newtons (or pounds in the British system).

Mass

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 it, stop it, deflect it, or change in any way its state of motion.

Weight

The force upon an object due to gravity, mg. (More generally, the force that an object exerts on a means of support.)

Kilogram

The fundamental SI unit of mass. One kilogram (symbol kg) is the mass of 1 liter (1 L) of water at 4 degrees C.

Newton

The Standard International (SI) unit of force. One newton (symbol N) is the force that will give an object of mass 1 kg an acceleration of 1 m/s^2

Volume

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 the direction of the net force, and is inversely proportional to the mass of the object.

Free fall

Motion under the influence of gravitational pull only.

Terminal speed

The speed at which the acceleration of a falling object terminates because air resistance balances gravitational force.

Terminal velocity

Terminal speed with direction specified.

Newton’s third law

Whenever one object exerts a force on a second object, the second object simultaneously exerts an equal and opposite force on the first.

Components

Mutually perpendicular vectors, usually horizontal and vertical, whose vector sum is a given vector.

Momentum

The product of the mass of an object and its velocity.

Impulse

The product of the force acting on an object and the time during which it acts.

Impulse-momentum relationship Impulse is equal to the change in the momentum of the object that the impulse acts upon. In symbolic notation,

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:

Elastic collision

A collision in which objects rebound without lasting deformation or the generation of heat.

Inelastic collision

A collision in which objects become distorted, generate heat, and possibly stick together.

Friction

The resistive force that opposes the motion or attempted motion of an object either past another object with which it is in contact or through a fluid.