Chapter 2 - Motion

Physical Science – Introduction to Physics

What is Physics?

Chapter 2 - MotionTwo things must be measured to study motion.

1. Position of an object at any instance.2. Time elapsed.

Position – requires a point of reference to define this. (Origin)

MotionScalar vs Vector

Scalar – a measurement of magnitudeVector – a measurement of magnitude and

direction.

MotionScalar Quantities

DistanceSpeed

Vector Quantities

Displacement (Change in Position or xf – xi)

VelocityAccelerationForce

Motion – Constant VelocityGraphing and Analysis 101 – Linear Relationships

Slope = velocity

Is velocity changingor constant?

Linear Equation Equation for this graph

y = mx + b xf = vt + xi

Begin with this motion.Write the mathematical relationship.

x (m)

t (s)0

What does the y-intercept represent?.

x (m)

t (s)0

Write the mathematical relationship for this motion.

x (m)

t (s)0

xf = vt + xi

x (m)

t (s)0

t

t

xx

What does the slope of this line tell you?

Slope =

t

t

xx

Slope =

t

t

xx t

x

Slope of a Position-Time Graph = Average Velocity

Slope =

t

t

xx

t

x

Since the relationship is a straight line, any 2 points may be used to find the

slope.

This average velocity...

x

t

x

t

The average velocity equals the velocity for any time interval if the position-time

graph is a straight line.

t

x

MotionWhat would a position – time graph look like for an object that is speeding up?

Since slope represents the velocity, the slope would have to constantly increase.

What would a position time graph look like for an object which is slowing down?

Decreasing slope.