This is for IGCSE Double Award Physics (EDEXCEL), tailored to the 2009 specification. If you spot any mistakes, please let me know, thank you! I hope you find this useful! :)
This blog is no longer updated as I've finished IGCSEs in 2012. I may sometimes reply to questions if you comment or email me, but not guaranteed. I hope what I had time to post back during IGCSEs helps anyway!! :)
a) Movement and position 1.2 understand and use distance-time graphs
Distance -time graphs
The gradient of a distance-time graph=speed
Distance isn't increasing-gradient=0, hence speed=0---->object is stationary (not moving)
The steeper the graph, the greater the speed as the gradient is steeper.
If the graph is curved, then the speed must be changing. If it is curving upwards (blue line), the speed is increasing, if it is curving downwards, the speed is decreasing. So the gradient of the graph also tells us how the speed is changing.
Instantaneous speed=How fast an object is moving at a particular instant.
The gradient of the tangent at a point on the distance-time graph gives us the instantaneous speed.
1.3 recall and use the relationship between average speed, distance moved and time:
average speed=distance moved/time taken
1.4 recall and use the relationship between acceleration, velocity and time:
acceleration=change in velocity/time taken
where v=final velocity
1.5 interpret velocity-time graphs
1.6 determine acceleration from the gradient of a velocity-time graph
the gradient at a point on the velocity-time graph gives you the acceleration
1.7 determine the distance travelled from the area between a velocity-time graph and the time axis
basically, the area under a velocity time graph = distance travelled