Thread: Finding Formula for Velocity

I have a word problem stating a jet needs a speed of 200 mph to take off
if it can accerlate from 0 to 200 mph in 30 seconds

how long must the runway be (assume assume constant acceleration)

How would I find a proper formula for velocity

Assuming Constant acceleration a(t) = 20/3

Integrate to find velocity

then v(t) = 20/3 t since the initial velocity is 0 this is the velocity.

Integrate to find position (in this case same as distance)


d(t) = 10/3 t^2

d(30) = 3000

how did you get 20/3

20/3 won't really work because the time units are different; . You'll have to convert it to , or some other units that you'll feel most comfortable with.

Originally Posted by sk8erboyla2004

how did you get 20/3

Well, think of acceleration as the slope of the velocity graph, or in other words, the change in velocity over the change in time. He did:

argh !!! mixed units was thinking 200/30

200mph = 293.3ft/sec

it shoud be 293.3/30 = 9.78

v(t) = .978 t

then d(t) = .489*t^2

d(30) = 440 ft