This document discusses uniform rectilinear motion. It defines different types of motion including rectilinear, curvilinear, and random motion. Distance is defined as a scalar quantity representing how far an object has moved, while displacement is a vector quantity that includes both distance and direction. Uniform motion refers to motion at a constant speed in a single direction. Graphs of distance-time and velocity-time relationships are used to analyze motion. The average velocity and speed can be calculated from these graphs by determining slope.

1. Chapter 9: Uniform Rectilinear Motion

2. Types of Motion
Rectilinear:
Motion in a straight
line path. E.g. an elevator.
Curvilinear: Motion in a curved
path. A ball being thrown.
Random: A combination of the
above. A leaf in the wind.

3. Distance and Displacement
 Distance
travelled depends on position.
 Distance is a scalar quantity.
 It is always positive.
 E.g. d = 5 km

4. Vector Diagrams

5. Activity
 Page
207, Q1. Orally,
 Q. 2-5, on paper

6. Uniform Motion
 The
simplest motion is straight line motion in a specific
direction at a constant speed.
 When both speed and direction remain the same, it
is called uniform motion.
 Speed is a scalar quantity, = distance/time.
 Velocity is the vector quantity denoting speed and
direction.
 Velocity is the displacement of an object per unit of
time.
 V = Δd/Δt, Δd - displacement, Δt – time interval.

7. Random Motion
 The
motion of these particles are random
because their speed and direction
change.
 This is an example of the Kinetic Molecular
Theory (Chemistry).

8. Graphing Distance-Time
 Time
is independent and on the x-axis.
 Distance depends on time and is on the yaxis.
 The slope of the graph gives us the speed.
 If it was a displacement-time graph, slope
would give the velocity.

9. Activity
 Page
 Lab
209. Q 1 - 3
Experiment – Can You Walk in a
Uniform Way – Ticker Tape

10. Graphing Velocity
 Velocity
is considered to be dependent
on time.
 Average velocity = total displacement
total time
 ‫ע‬av
= Δd/Δt

11. Average Velocity & Speed
 This
is done by taking the slope of a line at
two different points.
 Average velocity = ∆ displacement
∆ time
 Unit = m/s [direction]
 Average speed = ∆ distance
∆ time
 Unit = m/s

12. Average Velocity:
Uniform Acceleration
 Average
Velocity during uniform
acceleration can be calculated by taking
the mean of 2 velocities.
 vavg = v2 + v1
2
P. 209, Q 1-3

13. Distance & Speed
 We
already know that speed = distance

time
 So distance = speed x time
 Distance can be determined by the area
under the curve of a velocity-time graph.

14. Exam Question
 What
is the displacement after 25 s?
Velocity (m/s)
20
15
10
5
0
-5
0
5
10
15
20
25
30
-10
-15
Time (s)

15. Activity
 Page
213, Q. 1-5
 Page 215, Q 1-4

16. Summary
 Some
motions can be seen easily; other
motions must be observed using other
senses or devices.
 The trajectory is the path of a moving
object.