Units:

Types of Units:

• British Engineering (foot, slug, pound)
• MKS = Meter Kilogram System (meter, kilogram, Newton) Science Standard
• CGS = Centimeter Gram System

Mass: 1 kilogram (kg) = 1000 grams (MKS) Mass is a measurement of stubbornness.
Newton's First Law: Objects at rest tend to stay at rest, and objects in motion tend to stay in motion, unless acted on by some force.
In the British system, the unit of mass is the slug.
1 slug = 14.6 kg

Force: Units:

• British: pounds (abbreviated lbs.)
• MKS: Newtons (N)

1 N = 0.22 lbs.
Newton's Second Law: Force = Mass x Acceleration, or
F = ma, where acceleration is a change in motion. This can be in the form of an object speeding up, slowing down, or changing direction.

Weight: is a gravitational force due to the natural attraction between two masses. The weight of an object on Earth is due to the attraction of the object to the Earth. ( In general relativity, a mass causes time and space to curve and we perceive that curve as a gravitational attraction.)
F = G x M x m/R^2, where M = mass of the earth, m = mass of the object, and R = radius of the earth.
(G x M)/R^2 is defined as g, the acceleration due to gravity.
British System: Pounds = (mass)x(g), where mass is in slugs and g = 32 ft/s^2.
MKS System: Newtons = (mass)x(g), where mass is in kilograms and g = 9.8 m/s^2.

Displacement: How far something has moved.
British: 1 foot = 12 inches
MKS: 1 meter = 100 cm.
Conversions: 1 meter = 3.28 feet
2.54 cm = 1 inch

Velocity: is a speed with a direction.
Velocity = displacement/time. Typical MKS units of velocity are m/s, km/hour, etc.
Typical British units are ft/s, miles/hour, etc.

Acceleration: A change in velocity of an object. This change can be either a change in the speed or a change in the direction or both. Acceleration has units of length/time^2 .
Acceleration = change in Velocity/time. Typical MKS units of acceleration are m/s^2.
Typical British units are ft/s^2

Work and Energy:

The MKS unit of energy is the Joule (J).
Work = (Force)x(displacement)
1 Joule = (1 N)x(1 meter)
The British unit of energy is the foot-pound, or ft-lb, where
1 ft-lb = 1.26 J

Types of Mechanical Energy:

Kinetic Energy: energy of an object in motion.
K.E. = 1/2mv^2, where m = mass and v = velocity.
Potential Energy: Stored energy of an object.
P.E. (Of Earth's gravitation) = mgh, where m = mass, g = acceleration due to gravity, and h = displacement, in this case height.

Heat Energy
MKS: 1 calorie = amount of heat required to raise 1 gram of water 1 degree Celcius. (Note: 1 food Calorie = 1 kilocalorie.)
British: 1 BTU = amount of heat required to raise the temperature of 1 lb of water by 1 degree Fahrenheit.
1 BTU = 252 calories.

Power:
Power is Energy/time. The MKS Unit for power is a watt. 1watt=1joule/sec

For Other definitions try this Glossary of physical terms