Terms and Units

Force: Mass x acceleration (F=ma)

The force required to put a body in motion or to change the velocity or direction of a body in motion
- mass: The measure of an object's inertia, resistance to motion
  - Units
    - Kilogram (kg) = 1000 grams(g) = .0685 slug
    - slug=14.59 kg
- acceleration: rate of change in velocity (m/sec-sec or m/sec²)
Units of force
- Newton = kg-m/sec²
- 1 N = .225 lbs, the approximate weight of one apple
- l lb = 4.448 N
Weight: Mass x acceleration due to gravity (9.8 m/sec²)

Stress/Pressure: Force per unit area (F/A)

Units of stress/pressure
- 1 Pascal (Pa)=1 Newton/m²
- 1 Kilopascal (kP) = 10³ pascal
- 1 Bar = 100 kPa
- 1lb/in² = 144 lb/ft² = 6.895x10³ Pa
- 1 atm = 1.013x100 kPa = 1.013 bar
- Stresses important to normal glacial flow range from 50 kPa (.5 bars) to 200 kPa (2 bars) (Patterson, 1994)

Energy = Work

Energy is the ability to preform work by applying a force over a distance (E=Fxd)
Units of energy and work
- 1 joule (J) = 1 N-m
- ft-lb =1.356 J

Heat Energy: Internal energy (particle energy)

The internal energy moving between masses as a result of their differences in temperature
Units
- Kilocalories (C) = the heat required to increase a kilogram of water from 14.5 to 15.5°C
- 1kcal = 4185 Joules

Discharge (Q): The volume rate of flow through a cross-section per time.

Q=KIA (K = conductivity, I = gradient, A = cross sectional area)
The same equation applies to the discharge of heat, glacial ice, and water
Units
- Thermal Discharge: Watts (W)=kcal/sec
  - Thermal conductivity =kcal/(m-sec-°C) or W/(m-°C)
- Stream and Glacial Discharge: cfs = f³/sec

Convertit Process Associates Calculator A Dictionary of Units GlennBrook South Physics Classroom

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Lindley Hanson (email) Last Modified 2/25/00