Friction opposes

the motion of matter by solids. Example: The brakes on you car or rubbing your hands together.

Drag opposes the motion of

matter by liquids or gasses. Example: A ball dropping through air or water pushing against a submarine.

Weight is

the pull of gravity. Example: Things weigh more on earth than on the moon due to the fact the Earth weighs more so it has more gravitational pull.

Mass is often confused with

weight.  The mass stays the same regardless of the location.

The force of gravity pulls all objects

to Earth at the same speed until they hit terminal velocity. Without air, like on the moon, objects would fall at the same speed.

The force of gravity was first studied

by Galileo Galilee at the Leaning Tower of Pisa.

Potential energy is

energy at rest. It potentially could do work, like a rock resting on a cliff, a stretched rubber-band, a "loaded" spring, etc.

Kinetic energy is

energy in motion, like a rock falling, electrons in motion, a spring unloading, etc.

Centripetal force is

a circular motion force. The faster you spin an object the more centripetal force there will be. An example would be a car going around a sharp corner.

Acceleration is a positive change in

speed or velocity. You go faster (for the most part).

Deceleration is a negative change in

speed or velocity. You go slower (for the most part).

Momentum is found by multiplying mass times

 
velocity. You may not create or destroy momentum; you may only change it. It is hard to change the momentum of big objects (+ -).

Speed may measure it by knowing the

distance and dividing it by the time. Example - 33 mps.

Velocity is a three-dollar word for speed, except

that velocity has direction and speed. Example - 33 mps north.

Newton’s Laws of Motion:

The first law is also called the law of

inertia or keep things the same. An object doing nothing will continue to do nothing or an object in motion will stay in motion until acted upon by another force.

The second law is called the

 
dump truck law. It takes more force to move a dump truck than a small dump truck. This law further states that is also harder to stop a dump truck than a small car.

The third law is called the law of

 
action reaction. For every action there is an equal and opposite reaction. Example – When a gun goes off the bullet goes one way and the gun kicks back the other way.

Simple Machines:

A compound/complex machine

has two or more simple machines that could make the job easier, like a pencil sharpener.

A simple machine is

 
one or two parts that make a job easier. Levers, screw, wheel and axle, inclined plane, wedge and pulleys are simple machines.
 

Mechanical advantage (MA) is the number of

times a machine multiples the effort.

#1a.) First class levers have the 

fulcrum between the effort and the load.

You may increase the MA by

moving the fulcrum by the load (lengthening the effort arm). Example – a seesaw.

#1b. Second class levers have the 

load between the fulcrum and the effort. 

You may increase the MA by 

moving the fulcrum by load or by lengthening the effort arm. Example- Wheelbarrow.

#1c. Third class levers have the

effort between the fulcrum and the load.

You may increase the MA by

moving the fulcrum away from the effort (lengthening the effort arm). Example – your arm.

#2. An inclined plane is like a

ramp.

Increase the MA of an inclined plane by

lengthening the slope to make it more gentle.

#3. Wedges are often confused with inclined planes, 

but the difference is that a wedge splits things apart like a knife.

You may increase the MA of a wedge by

lengthening the slope to make it more gentle.

#4. Screws have an inclined plane

wrapped around a cylinder.

Screws may increase their MA by

using a gentle slope with a lot of threads. Example – bolts or screws of course.

#5. A wheel and axle has a wheel attached

to the axle and arm, like a water well.

Increasing the MA may be done by

increasing the resistance arm or by having a larger radius wheel.

#6a. Fixed pulleys can not have their MA improved, they only

 
 
change the direction of the load. If you pull down with 100 Newtons of force you would only be able to lift 100 Newtons at the most, probable less after you take into account friction.

You may not increase the MA.

 of a fixed pulley.

#6b. Moveable pulleys have the lower pulley move

 
 
 
 
with the load. Four strands on the lower pulley would mean a mechanical advantage of four, and it would take about 25 Newtons of force to lift the 100 Newtons because you divide by four. Three strands would mean a mechanical advantage of three, and it would take 33 Newtons of force to lift it. Etc.

You may increase the MA by

using more strands of rope on the moveable pulley.

Motion:

Vertical motion is the

upward or downward motion of an object.

Horizontal motion is the

sideways motion of an object.

 Energy Laws:

First Law of Thermal Dynamics states that

energy cannot be created or destroyed, it can only be changed from one form to another.  The energy is given off involves heat and maybe something else.

Another name for the First Law of Thermal Dynamics is

The Law of Conservation of Energy.

The Second Law of Thermal Dynamics states

 
 
that during the energy conversion heat is produce that warms the surroundings.  Example:  A woman running a race uses some energy to run and some energy is given off as wasted heat.

Perpetual motion attempts to

make as much energy as it uses, thus it could stay in motion.  There has never been a perpetual motion machine due to friction, gravity, etc.

The Law of Falling Objects states that

all objects fall toward the earth at the same speed until one of them hits its terminal velocity.  Shape may have an influence due to drag.