Calculus  another question
posted by Stuck on .
"Margaret has found that by a proper choice of gears she can steadily increase her speed on her bike. One day she sets out and, ten minutes later, she achieves her cruising speed of 30km/h by increasing her speed steadily. How far did she travel in that ten minutes?"
I don't know how to begin this!

a = acceleration
v = Vi + a t
d = Xi + Vi t + (1/2) a t^2
30 = 0 + a t = 0 + a (10/60)
a = 30*60/10 = 180 km/hr^2
d = 0 + 0 + (1/2)(180)(10/60)^2
= 90/36
= 2.5 km 
By the way the average speed was 30/2 = 15 for 1/6 of an hour
15/6= 2.5 
Thank you! So the constants (Vi and Xi) are 0...why is that?

Xi is where you started, might as well be at the origin.
Vi is your speed at the start. Implied zero.