## saifoo.khan 4 years ago Quick Question, Area under speed-time graph is the distance travelled?? T or F?

1. anonymous

t

2. dumbcow

True speed = distance/time *time = distance

3. anonymous

umm is this a physics question?

4. saifoo.khan

No, this is Math,

5. anonymous

okies :)

6. saifoo.khan

Now it's fine. :D

7. anonymous

Distance to me is an absolute value. No directional sense. So, as I pointed in the link and as MrYantho suggested, I like displacement.

8. saifoo.khan

Okay!! (: can u solve the question in the picture?

9. anonymous

Saifoo - sorry man....I did this stuff 22 years ago and it is hard to remember. I can google it up and get it. But, you or someone current is going to be a lot better at it.

10. saifoo.khan

No worries. Thanks for trying! :)

11. anonymous

sorries me cant do it either :(

12. saifoo.khan

np

13. anonymous

um its just at constant speed not instantaneous right?

14. saifoo.khan

first it has increasing speed, then constant speed, i want to draw the distance-time graph for this.

15. anonymous

could you wait a bit ill try to help this stuff is in my physics book

16. anonymous

its the math it uses

17. saifoo.khan

This might help,

18. anonymous

the formula you just use is a regular d=r/t

19. saifoo.khan

idk. this is the screenshot form the marking scheme.. i have no idea how they did that.

20. anonymous

formula for aceleration final speed= initial speed + speed change

21. saifoo.khan

$a = \frac{v-u}{t}$Right?

22. saifoo.khan

But how we will draw the speed-time? :l

23. anonymous

on you graph y is the speed x is the time

24. saifoo.khan

wait. sorry.. that is already drawn in the question.. i want displacement time. hehe,

25. anonymous

displacement ? umm i dont understand displacement from what?

26. saifoo.khan

27. anonymous

it is cut off

28. anonymous

can you type the rest it?

29. saifoo.khan

The first part says to sketch the region whose area represents and stuff.. t And the cut off part says "find the value of T"

30. anonymous

first time change of 1 cyclist s=(v) (t) + 1/2 ( a)( t) use formula again to find displacement again of the cyclist

31. anonymous

then you may probably use d=rt to figure out the rest of the stuff i think this is how it is done :\

32. anonymous

it's true that the area under speed-time graph is distance you can get this from this formula d=vt |dw:1327401093475:dw|

33. dumbcow

The line for cyclist P is v = 2t, since the constant acceleration is given as 2 the displacement is 16 and the area under the curve is the displacement Area = vt/2 = 16 vt = 32 substitute v=2t 2t^2 = 32 t^2 = 16 t =4 Therefore, cyclist Q starts 4 sec after when cyclist P is going 8 m/s