Evans SPH 3U1

Physics Grade 11

Unit 1: Forces and Motion

Note 6: Motion in Two Dimensions

Reference: Chapter 2.1, 2.2

Vector Direction Notations:

        tail                          head or tip

   1)   [N60E]   [E30N]    some books will also call these the following (but I do not like).......[30 N of E]    [60 E of N]

   2)   [W60S]  [S30W]   some books will also call these the following (but I do not like).......[30 W of S]    [60 S of W]

    Note:     In words [N60E] reads as "north 60 degrees east"

                 In words [30 N of E] reads as "30 degrees north of east" (but I will not use this one although you should be familiar with it)

Adding Vectors:

Vectors are added tip(head) to tail. The resultant vector is drawn from the tail of the first vector to the head of the last vector. Fig. 3.5 pg.79

Subtracting Vectors:

Subtracting is really the same as adding. i.e. Show example

If you need to add more than two vectors you should use the component method.............

Components:

Review trig ratios sine, cosine, tangent (overheads)

Adding with components:

- Resolve vectors into x (horizontal) and y (vertical) components

- Assign directions

- Add horizontal (x) components

- Add vertical (y) components

- Use pythagorean theorem to find the MAGNITUDE of the resultant i.e.

- Use trig ratio to find the DIRECTION of the resultant

Example 1: A student walks 5.0 km [N30E], then 4.0 km [S40E] and then 2.0 km [W]. What is the student's resultant displacement?

Example 2: If the student took 2.5 hours for the trip, what was her speed and velocity?

Adding with Cosine Law and Sine Law:

Pg 65 #8 (scaled)

Pg 75 #1-3

Pg 75 #4,5,6 (components and cosine/sine law)    #7 (components)

Pg 75 #8,9

Handout Motion in 2D