VECTORS

Chapter 4.1

Scalar or Vector?

What am I, a scalar or vector quantity? Scalar – only magnitude Vector – magnitude AND direction

Velocity, Force, Acceleration, Displacement

5 mph 5 mph north 15 m/s northwest 1.2 N west 10 m/s

Vectors

Vectors have magnitude and direction. They add or subtract depending on their directions.

Parallel vectors are pretty simple:

50 N

50 N= 100 N

+

50 N

50 N=+ 0 N

What if the vectors are NOT parallel:Example: What if I walked 16 km

East and 12 km NorthThe result is a NET movement of 20 km Northeast 16 km East

12

km

No

rth

20 km Northeast

Component Vectors

Resultant Vector

To work with vectors, it is important to know how to perform vector addition both graphically and analytically. Graphically – draw vectors to scale and

measureAnalytically – use formulas

When 2 or more vectors act on an object, they act independently of one another.

Their combined action will result in a net effect.

The purpose of vector addition is to determine the net figure and direction.

The net figure is called the “resultant.”

The best way to determine the measurement of a resultant is mathematically, but sometimes it is necessary to draw the vectors to scale and measure the resultant with a ruler and protractor.

Let’s look at an example…

Let’s examine a picture of a boat crossing a river.

The boat is moving due east at 8.0 m/s, and the river is flowing due south at 5.0 m/s.

Find your resultant and direction