VTgraphs

Graphing Velocity

Okay back to drag times we go, lets compare some cars !!

What one do you wanna know about?

http://www.dragtimes.com/compare.php

Remember to take down the data of 4 different cars!

There are pictures of the cars with a * on them!

Okay what problems do we have with the data ??

Whats E.T. & M.P.H. ??

Problem ?

Its in Imperical form, how do we change it ?

Well one foot = 0.3048 m or 1m = 3.2808ft

and Miles per hour !

Convert the miles to meters 1 mile = 1609.34m

So the MPH x 1609.34 is the number of m it goes in 1 hour, we would rather deal in m/s

So how many second in an hour?

60 Mins, each min has 60 sec ..... 60 x 60 = 3600,

So divide the number of meters in an hour by 3600, to see the m/s

This will give us the speed in units we can use!

or go here for all the metric converstions

http://www.worldwidemetric.com/metcal.htm

Lets draw 4 graphs of the 4 cars you chose!

Use the data of the speed and the time to plot a graph of the speed against time!

Remember to get the axes to have the same scale the whole way along each axis

Do these car accelerate linearly ?

How do you know?

What happens the speed as the time passes ??

When does it increase the most ?

What do we call it when we change speed ?

How could I find out my A_________ ?

Slope

hint if it goes through the origin take (0,0) as X₁,Y₂

So we can find the acceleration at various stages in the cars journeys, there are two accelerations for each car and 4 cars, go on work 'em out

Is there anything similar with all four cars graphs ??

Want to colour them in ??

Area! Space! Bit under the Line!?

How do we find area ??

Yes! but for a Triangle

and even odder shapes?

Odder shapes are always just Compounds of basic shapes! Usually!

The shape in the graph is just a triangle sitting on top of a rectangle,

Find the areas of the 4 Cars.

Remember only use the eqs of motion when the body is accelerating (or decelerating)

A car travels from p to q along a straight level road.

It starts from rest at p and accelerates uniformly for 5 seconds to a speed of 15 m/s.

It then moves at a constant speed of 15 m/s for 20 seconds. Finally the car decelerates uniformly from 15 m/s to rest at q in 3 seconds.

(i) Draw a speed-time graph of the motion of the car from p to q.

(ii) Find the uniform acceleration of the car.

(iii) Find the uniform deceleration of the car.

(iv) Find |pq|, the distance from p to q.

(v) Find the speed of the car when it is 13.5 metres from p.

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