we had to watch an animation which showed two balls, each traveling on a straight horizontal line at different speeds.

Question

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), (3,5), (4,7)

it is asked:

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 6 seconds to reach the finish line,but I don't think this is right

thanks!

Answer 1

> (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