Vectors

Some things we talk about in Physics are fully described by a

numberand aunit. A few examples might be2.6 kg of apples from the grocery store

18.5 yd

^{2}of carpeting for your apartment15.8 m

^{2}of carpeting for your apartment15.2 gallons of gasoline at the filling station

28.3 liters of gasoline at the filling station

35 lb/in

^{2}air pressure in your tires135 kPa air pressure in your tires

98.6

^{o}F is normal body temperature39

^{o}C is normal body temperatureThings like these are called

scalars. Scalars are fully specified or completely described by anumberand aunit. (Don't forget theunit!Units are important!).Some other things we talk about in Physics also need a

direction. Some examples includeMontreal is 600 km

eastof Toronto.Chicago is 300 km

northof Charleston.The wind is blowing 30 km/hr from the

north(brrrrr!)The force of gravity is 500 N,

down.The table's support force if 350 N,

upward.The force of friction is 110 N,

to the left.The string exerts a force of 55 N,

at 40^{o }above the horizontal.Things like these are called

vectors. Vectors need adirectionto fully describe them. Vectors require anumber, aunit, and adirection.(Don't forget theunits!Units are important!).

(C) 2003, Doug Davis; all rights reserved