Linear Motion

1
Linear Motion

• Objects Moving in a Straight Line

2
Unit 2 Goals

• In this unit you will
• Represent motion through the use of words, motion
  maps and graphs.
• Use the terms position, distance, displacement,
  speed and velocity in a scientific manner to
  describe motion.
• In physics, the study of motion is sometimes
  referred to as KINEMATICS.

3
Picturing Motion

• Perceiving motion is instinctiveyour eyes pay
  more attention to moving objects than to
  stationary ones. Movement is all around you.
• Movement travels in many directions, such as the
  straight-line path of a bowling ball in a lanes
  gutter, the curved path of a tether ball, the
  spiral of a falling kite, and the swirls of water
  circling a drain.
• When an object is in motion, its position
  changes. Its position can change along the path
  of a straight line, a circle, an arc, or a
  back-and-forth vibration.

4
Motion in a Straight Line

• A description of motion relates to speed and
  time. You must be able to answer the questions of
  where? and when? an object is positioned to
  describe its motion.
• Position location

5
Movement of a car
In the picture below, the car moves from point A
to point B.
6
Vectors and Scalars

• A scalar quantity is just the magnitude (amount).
• Speed is a scalar.
• For example 50 meters/second.
• A vector quantity indicates not only the amount,
  but the direction, too.
• Velocity is a vector.
• For example 50 meters/second, North.

7
Distance and Displacement

• Distance refers to how far an object travels.
• This is a scalar quantity.
• -For example the car traveled 35km.
• Displacement refers to how far the object
  travels, but also adds direction.
• This is a vector quantity.
• -For example the car traveled 35km, North.

8
Speed

• Speed is how fast an object is traveling.
• This is a scalar quantity.
• -For example 55m/s
• Average speed speed over a time interval.
• Instantaneous speed speed right now

9
Velocity

• Velocity is how fast an object is traveling, but
  direction is also indicated.
• -For example
• The train traveled at 55m/s, South.

10
A helpful website

• www.Physicsclassroom.com
• Designed to help you with definitions, concepts
  and examples to try.
• We will be using this site in class often, but it
  is also accessible from home!
• For Unit 2 Linear Motion
• See Physics Tutorial 1-D Kinematics

11
What is a Motion Map?

• A motion map is a series of images that
  represents the movement of some object.
• It consists of a particle (dot) to represent the
  position of an object and an arrow to represent
  the speed and direction the object is moving.
• See the motion map reading handout.