# physics

posted by .

we had to watch an animation which showed two balls, each traveling on a straight horizontal line at different speeds.
the graph of position vs time and velocity vs time are given.

The red ball has a linear graph and the coordinates are (0,0), (1,5), (2,10), (3,15), and (4,20)

for the blue ball:(0,0), (1,1), (2,2.5), (3,4.5), (4,7)

If the motion was allowed to continue the blue (lower) ball would reach the finish line (20m) at some time Δt after the red ball. What is Δt?

i though that it would take the blue ball around 9 seconds to reach the finish line,but I don't think this is right

thanks!

• physics -

here is the graph given can be seen if you search

• physics -

Sam, The response to
"physics - sam, Thursday, May 28, 2009 at 11:43pm"
had been posted last night, even with a suggested correction that you have made this morning.
Would you like to check back before we continue?

• physics -

physics - PC, Friday, May 29, 2009 at 12:18am
Here is a copy of the previous response.

> (0,0), (1,1), (2,2.5), (3,5), (4,7)
Could you check the data for the blue ball to see if it is not:
(0,0), (1,1), (2,2.5), **(3,4.5)**, (4,7)

If that's the case, you will find that the function of the blue ball is
y=f(x)=(x^2+3x)/4
in which case you can easily solve for
f(x)=20

• physics -

I did that, and the answer came out to be 10.57, which isn't right.
I wasn't sure if a picture of it would help at all?

• physics -

I have uploaded a graph but I am unable to show the link as I do not have privileges to do so. Sorry.

• physics -

The answer is the solution to the equation

(x^2+3x)/4=20

Do you have difficulties finding the solution to the above equations?

• physics -

Hello Sam, here'is the link to the graph you requested:
http://i263.photobucket.com/albums/ii157/mathmate/parabola.png