motion graphs n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Motion Graphs PowerPoint Presentation
Download Presentation
Motion Graphs

Loading in 2 Seconds...

play fullscreen
1 / 30

Motion Graphs - PowerPoint PPT Presentation


  • 71 Views
  • Uploaded on

Motion Graphs. Distance and Displacement. Distance is a scalar quantity! is how far something has moved. is measured in metres etc. Displacement is a vector quantity. is how far an object has moved from its starting point and in what direction.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Motion Graphs' - savea


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide2

Distance

and

Displacement

slide3

Distance

    • is a scalar quantity!
    • is how far something has moved.
    • is measured in metres etc.
  • Displacement
    • is a vector quantity.
    • is how far an object has moved from its starting point and in what direction.
    • measured in metres but also has a direction.
    • is the (straight line) distance between 2 points with the direction given too!
slide4

If the bear skis the 7 metres to the tree then back to the start and then all the way to the house, what distance would he have gone? _______m

slide5

What would his displacement from the starting point be ? ___________ m in an easterly direction.

slide6

Speed

and

velocity

slide7

Speed is a scalar quantity!

    • It is how fast something has travelled
    • It is measured in metres/second or km/hour.
  • Velocity is a vector quantity.
    • This is how fast and in what direction something travels IN A STRAIGHT LINE!!!
    • This is measured in m/s or km/h but also has a direction.
slide8

Speed

    • If a car travels 150 km in 2 hours then calculate the average speed of the car:

Average Speed = distance travelled/ time

= d/t

= 150 km/ 2 h

= 75km/h

Or write it like this:

= 75 km h ⁻¹

slide9

Velocity

    • If a plane travels 480 km in a southerly direction for 2 hours then calculate the average velocity of the plane:

Average velocity= distance travelled in a straight line time

Vav = s/t

= 480 km/ 2 h South

= 240km/h South

Or write it like this:

= 240 km h ⁻¹ South

slide10

Remember that if an object is going at a constant speed but changes direction (turns) then its velocity changes!!

slide11

All these abbreviations – what do they stand for???!!!

d = distance

s = displacement

t = time

v= velocity or final velocity

u = initial velocity

a = acceleration

slide12

Motion graphs

It is often easier to show the motion of an object with a graph rather than with words.

There are 2 types of graph we will look at:

  • Displacement – time graphs or distance – time graphs.
  • velocity - time graphs or speed- time graphs.

VELOCITY (v)is simply speed in a given direction

DISPLACEMENT (s) is the distance in a given direction

slide13

With both types of graph, time is plotted on the x axis.

  • The further to the right along the x axis we go – the longer the time from the start!
  • Velocity, distance etc are always plotted on the y axis.
  • We assume the initial direction of motion to be positive.
slide14

Distance (m)

0 1 2 3 4 5 6 7 8 9 10 11

A body at rest.

That is it is stopped or standing still!

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide15

An object moving at constant speed.

Constant speed because the lines are straight!

Which line shows the object going fastest?

Distance (m)

0 1 2 3 4 5 6 7 8 9 10 11

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide16

Speed is given in m/s so we can work out the speed here by saying speed = rise/run = distance/time.

Work it out for each.

Distance (m)

0 1 2 3 4 5 6 7 8 9 10 11

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide17

A body accelerating!

You can see that the speed is increasing: the distance travelled is more each second so this shows it is accelerating!!

Distance (m)

0 1 2 3 4 5 6 7 8 9 10 11

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide18

Lets look at an example:

First we will give the information in words then as a

displacement – time graph.

Matthew starts from point A and travels at 2m/s for 3 seconds to point B. He then stops at point B for 4 seconds before going back towards point A at an initial velocity of -1.5m/s for 2 seconds then stopping at an intersection for 1 second before continuing to point A at -1.5 m/s.

Ok – lets look at this graphically!!!!!

slide19

Much Easier than words!!!

Distance (m)

0 1 2 3 4 5 6 7 8 9 10 11

Matthew’s trip

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide20

Lets do

some questions!

slide21

This axis has SPEED not distance on it!!!!

What is the difference between this graph and the ones we looked at before??

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide22

So what does this graph show?

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

It shows that the object is moving at a constant speed of 5.5m/s

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide23

What does this graph show?

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

It shows that the objects’ speed is increasing or the object is accelerating!

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide24

What does this graph show?

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

It shows that the objects’ speed is decreasing or the object is decelerating!

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide25

Which line shows faster acceleration? Green or blue?

Acceleration = speed/time so

Blue = 3m/s/s

Green = 1m/s/s

Steeper slope = faster acceleration!

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide26

Putting it all together:

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

Steady speed

Fast deceleration

Or

negative acceleration

Fast accn

Slow accn

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

slide27

What other information can we get from displacement – time and speed time graphs?

Speed (m/s)

1 2 3 4 5 6 7 8

Distance (m)

10 20 30 40 50 60

1 2 3 4 5 6 7 8 9 Time (s)

1 2 3 4 5 6 7 8 9 Time (s)

Gradient = rise/run = 7/7 = 1m/s/s = acceleration!!! Area under the graph = ½ time x speed

= s x m/s

= m

= distance travelled!!!

Gradient = rise/run

= 30/6

= 5m/s

= speed!

slide29

Work out the area under the line to work out the distance travelled

Speed (m/s)

0 1 2 3 4 5 6 7 8 9 10 11

0 1 2 3 4 5 6 7 8 9 10 11 12 time (s)

reading pages 3 to 4
Reading – Pages 3 to 4

Can you stick the sheet in too?