Physical Science Vocbulary

Force

A push or a pull

Natural Balance Point (NBP)

The point on an object where it will balance on a fulcrum.

simple machine

: A machine that gives you either a force advantage or a distance advantage or a direction advantage.

F(in)

Force you put in to a simple machine (effort)

F(out)

Force you get out of a simple machine (load)

Work

The F in or F out acting through a displacement

W(in):

Work in. The work you put into a machine

W(out)

Work out. The work you get out of a machine

Fulcrum

: (∆) The pivot point in a lever. Also called the axis of rotation.

1st class lever:

fulcrum in the middle; see-saw, hammer, scissors

2nd class lever:

Output force is between input force and fulcrum ex: wheelbarrow

3rd class lever:

fulcrum at the end, effort in the middle; tweezers, baseball bat

d(in)

: distance in. The distance over which the effort force moves

d(out)

: distance out. The distance over which the load travels

Distance advantage

: When a machine moves the load a further distance than you have to move the effort. The price you pay is that your effort must be greater than your load.

(IMA) : Ideal Mechanical Advantage.

The maximum mechanical advantage you can get out of
your machine. It can be found by the ratio of the d(in) over the d(out).

Force advantage

: When a machine gives you more force out (load) than force in (effort). The price you pay is that you get a distance disadvantage.

Direction advantage

: Most machines change the direction of the force out compared to the force in. SOMETIMES this is an advantage.

Compound Machine

: a combination of two or more simple machines. The F(out) of one becomes the F(in) of the next one in line.

Simple Pulleys

: 1st class levers

Positive work :

increases the energy of a system (positive energy flow)

Negative work

: drains the energy out of a system (negative energy flow)

Initial Mechanical Energy (Ei)

: The initial total useful energy available to the system Final

Final Mechanical Energy

Ef The final total useful energy available to the
system

Mechanical Energy (Ef)

: The final total useful energy available to the system

Acceleration

The name we give to any process where the
velocity changes. Since velocity is a speed and
a direction, there are only two ways for you to
accelerate: change your speed or change your
direction—or change both.

Balanced Force

Two forces acting in opposite directions on an
object, and equal in size. Anytime there is a
balanced force on an object, the object stays still
or continues moving continues to move at the
same speed and in the same direction

Distance

A scalar quantity that refers to "how much
ground an object has covered" during its motion.

Position

A place where someone or something is located or has been put. In physics, usually a number on an axis.

Force

any interaction that, when unopposed, will change the motion of an object

Free Body
Diagram

Show the relative magnitude and direction of all
forces acting upon an object in a given situation

Gravitational Force

The force of attraction between all masses in the universe; especially the attraction of the earth's
mass for bodies near its surface

Friction

Fs force of static friction between two surfaces that prevents those surfaces from sliding or slipping across each other, or, Fk force of kinetic friction Fk, always opposes the sliding motion and tries to reduce the speed at which the surfaces slide across each other

Inertia

This tendency to resist changes in their state of motion. Newton's 1st law of motion or the law of inertia.

Mass

Quantity of matter in a body regardless of its volume or of any forces acting on it.

Net Force

Sum of all the forces acting on an object.

FNET = F1 + F2 +...+ FN

Newton's laws of motion

1st law: Every object persists in its state of rest or uniform
motion in a straight line unless it is compelled to change
that state by forces impresses on it.
2nd law: Force is equal to the change in momentum (mV)
per change in time. For a constant mass, force equals
mass time acceleration F=ma
3rd law: For every action, there is an equal and opposite
reaction.

Scalar

Quantities that are fully described by a magnitude (or numerical value) alone. A number
where direction doesn't matter

Speed

A scalar quantity, is the rate at which an object
covers distance

System

A system is a portion of the universe that has
been chosen for studying the changes that take
place within it in response to varying conditions.
Everything outside the system is known as the
environment.

Unbalanced Force

Forces which speeds up, slows down the
objects, or makes them change their direction

Time

What a clock reads. In classical, non-relativistic
physics it is a scalar quantity and, like length,
mass, and charge, is usually described as a
fundamental quantity.

Vector

Quantities that are fully described by both a
magnitude and a direction. A number where
direction matters

Velocity

Change in position divided by the time
of travel. Distance traveled by an
object per unit time in a particular
direction

Displacement

A vector quantity that refers to "how far out of place an object is"; it is the object's overall

change in position.