do now: distinguish between distance and displacement. which directions are positive? which...

Do Now:

• Distinguish between distance and displacement.

• Which directions are positive?

• Which directions are negative?

Kinematics = study of motion

How many dimensions do we live in?

4.

1. What is motion? Define it!

2. Are you in motion right now? Explain.

How do you know something is moving?

• Need frame of reference – backdrop.

Objects In Motion

change position in space, along x, y, z relative to reference frame.

• Symbol for change .

• Means subtract:

• x = xf - xi.

• Simplest form of motion is 1 dimensional or 1-d.

• Straight line motion .

Speed & Velocity

Speed & Velocity Scalar & Vector

• Speed rate an object covers

• distance – scalar (v)

• Velocity – rate of an object’s displacement - includes direction. (v)

Speed = total distance/timeSCALAR. No direction indicated.

speed = d tot /t tot.

Velocity = displacement/time VECTOR. Includes direction.

v = x/t,

v= s/t v = d tot /t tot.

Vel direction/sign = displacement.

Average Speed & Velocity

Text

• In class Problems pg 44 #1, 4, 6.

1. A car travels 200 km north in 1.8 hours, turns and drives 30 km south in 0.6 hours.

Calculate the average:

a. Speedb. Velocity

2. A bus travels 55 km west in 0.25 hours, stops for 30 minutes, turns and travels 145 km east. The eastward trip takes 2 hours. Calculate the average:

a. Speed

b. Velocity

Equations are for average not instantaneous velocity.

Only if object travels at constant velocity, average = instantaneous.

Read text pg 40 - 42

• Do Wksht Introduction to Motion

Take out HomeworkJot down the answer in you notes.

• What is the acceleration of a turtle moving east at 0.25 m/s.

• A car driving west at 20 m/s slows to a stop. What is the sign of the acceleration?

• If a car is moving to the east, can its acceleration be west? Explain and give an example.

Graphs of MotionPosition/Distance/Displacement – time

Constant v. What is the difference btw the 2

Starting point

Uniform/ constant velocityv = slope. Calculate the velocity.

Slope = 0

Constant vs. Changing speed

Displacement has direction includes neg quadrant.

Describe what is going on

Many objects in motion

Uniform/Constant Acceleration

Instantaneous velocity = slope of tangent.

Hwk Text Rd p 45 – 46. Do pg 69 #1 - 5, #10, #14.