Posted by **Stuck** on Thursday, April 1, 2010 at 7:53pm.

"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!

- Calculus - another question -
**Damon**, Thursday, April 1, 2010 at 8:15pm
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

- Calculus - another question -
**Damon**, Thursday, April 1, 2010 at 8:17pm
By the way the average speed was 30/2 = 15 for 1/6 of an hour

15/6= 2.5

- Calculus - another question -
**Stuck**, Thursday, April 1, 2010 at 8:56pm
Thank you! So the constants (Vi and Xi) are 0...why is that?

- Calculus - another question -
**Damon**, Thursday, April 1, 2010 at 10:17pm
Xi is where you started, might as well be at the origin.

Vi is your speed at the start. Implied zero.

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