Kinematics ( Definitions)

1
Kinematics ( Definitions)

• Aims
• Be able to recall the definitions of
  displacement, instantaneous speed, average speed,
  velocity acceleration.
• Be able to describe the difference between
  displacement and distance.
• 3) Compare and contrast average speed cameras
  and GATSOs

2
Kinematics ( Definitions)

• Displacement
• The distance travelled in a certain
  direction.
• Scale Drawings

100m ( 1cm)
300m ( 3cm)
3
Kinematics ( Definitions)

• Instantaneous Speed
• Instantaneous speed is the speed at an instant
  in time.

Distance
Time
4
Kinematics ( Definitions)

• Average Speed
• Average speed is the distance travelled by an
  object divided by the time taken to travel that
  distance.

S d/t
5
Kinematics ( Definitions)

• Find the definitions for Velocity Acceleration.
• What is the difference between average speed
  cameras GATSOs ?

6
Kinematics ( Graphs)

• Aims
• Be able to apply graphical methods to represent
  displacement, speed, velocity and acceleration
• Be able to determine velocity from the gradient
  of a displacement against time graph
• Be able to determine displacement from the area
  under a velocity against time graph
• Be able to determine acceleration from the
  gradient of a velocity against time graph.

7
Kinematics ( Graphs)
8
Kinematics ( Equations of Motion)

• Aims
• 1) Derive the equations of motion for constant
• acceleration in a straight line from a
  velocity
• against time graph.
• 2)Be able to select and use the equations of
  motion for constant acceleration in a straight
  line.
• 3) Apply the equations for constant acceleration
• in a straight line.

9
Kinematics ( Equations of Motion)
V
U
0
0
t
10
Kinematics ( Equations of Motion)
10m/s
Slope ?
0
t
4s
0
Slope 3m/s2
0
t
5s
0
11
Kinematics ( Equations of Motion)
v u at
When do we use this to solve problems ?
1) A car starts from rest and accelerates at
2m/s2 for 4 seconds . What will its final
velocity be ? 2) A car accelerates from 15m/s to
25 m/s in 10 seconds . What is its
acceleration? 3) How long will it take a car to
accelerate at 5m/s2 from 10m/s to 32m/s ?
12
Kinematics ( Equations of Motion)
s ½(u v)t
When do we use this to solve problems ?
1) How far will a car travel when it accelerates
from 8m/s to 20m/s in 8 seconds. ?
13
Kinematics ( Equations of Motion)
v2 u2 2as
When do we use this to solve problems ?
1) A car starts from rest and accelerates at
2m/s2 for 4 seconds, it covers 120m in this time
. What will its final velocity be ? 2) A car
decelerates from 30m/s to 10 m/s .It covers a
distance of 150m whilst doing this . What is its
deceleration? 3) How far will a car travel when
it accelerates at 2m/s2 and increases its
velocity from 17m/s to 34m/s.
14
Kinematics ( Free Fall)
1) Apply the equations for constant
acceleration to examine the motion of bodies
falling in the Earths uniform gravitational
field without air resistance 2) Explain how
experiments carried out by Galileo
overturned Aristotles ideas of motion. 3)
Describe an experiment to determine the
acceleration of free fall g using a falling body
15
Kinematics ( Free Fall)
What does this image tell us about an object in
Free Fall ? What graphs could we plot ? What
calculations could we do ?
16
Kinematics ( Free Fall)
Use the data below to plot 3 graphs. What do the
graphs show?
Time Height Displacement
0.00 20.00 0.00
0.20 19.80 0.20
0.40 19.21 0.79
0.60 18.25 1.75
0.80 16.96 3.04
1.00 15.37 4.63
1.20 13.53 6.47
1.40 11.48 8.52
1.60 9.26 10.74
1.80 6.90 13.10
2.00 4.43 15.57
2.20 1.88 18.12
Time Velocity
0.00 0.0
0.20 -2.0
0.40 -4.0
0.60 -6.0
0.80 -8.0
1.00 -10.0
1.20 -12.0
1.40 -14.0
1.60 -16.0
1.80 -18.0
17
Kinematics ( Free Fall)
18
Aristotle and Galileo
Galileo
Aristotle

• Explain how experiments carried out by
  Galileo overturned Aristotles ideas of motion.
• Include a description of the inclined plane
  experiment.

19
What we have Covered
Kinematics
20
What we have Covered
Linear Motion