Measuring the average speed of an object

[Griffy11]

Hi everyone,

http://img372.imageshack.us/img372/6093/img009h.jpg

With the above, I really have no idea other than the standard s=d/t formula, but I doubt that has anything to do with it for a question worth 3 marks, and then looking at the two questions below, it'd make no sense.

The other idea I had was finding the total time, then the area under the graph for d, giving you s=d/t again, but using the method I just described. Then 25c would be answered by saying that finding instantaneous speed required a tangent drawn to the point etc, as opposed to the whole area under the curve.

Is the idea of finding d and t using area under the graph right, or am I way off?

Thanks for the help in advance.

 

[Griffy11]

Bump. :)

 

[the pro]

dude look a) Vm=X-X0/T-T0=deltaX/deltaT so this is for the avarage speed .

 

[Griffy11]

I've never heard of this formula before, so it's something which we haven't covered in class yet. Hence - it can't be right.

 

[the pro]

ah i now , now it is about the uinits i wrote them in my lengauge but this formula is for the avarage speed but i don't now how to writte them in english sorry but it is the formula for avarage speed

 

[the pro]

and another thing the avarage speed u can discribe it like this if a car moves with a speed of 3 km/h at the start and 5 km/h at the end u can't put together 5 + 3 and get 8km/h then divide it by 2. 8:2=4km/h so the avarage speed now is 4 km/h so even if the car dosent achive to have this speed but it is simpel to tell that the car can end the road at this speed sorry for my english i now it is bad but it is my 4 lengauge and i am learning it now since 4 months but i see i get better

 

[Griffy11]

I'm aware that there is a formula for average speed (s=d/t), but something like that wouldn't cut it for a 3 mark question, especially when there's two follow-on questions after it. The question also asks how you would measure the average speed, rather than what average speed is.

Also, don't worry about your English, it's not that bad! ;)