Finding Force Needed for 200 km/hr

[Ashley1nOnly]

Homework Statement

Looking for F for 200 km/hr

Homework Equations

F=ma

The Attempt at a Solution

F-cv^2 = ma
F= ma +cv^2

v=200 km/hr

F= ma +c(200 km/hr)^2

so now I need to find a, from previous work I found that

t= (m/c)*(1/2 vter)*(ln[ (vter +v)/(vter-v)])

next I would solve for v and take the derivate to get a.

but I know that

v^2 =v0^2+2a( x -x0)

where

a= v^2-v0^2 / 2(x-x0)

I know that v=2000 km/ hr
v0=0 since it was at rest
x= final distance
x0=0 since it starts at the origin ​

 

[Charles Link]

See post 63 of https://www.physicsforums.com/threads/integration-help-on-physics-problem.955920/page-4#post-6060924 The speed of 200 km/hour should get reached rather quickly. They don't mean for you to accelerate at a constant rate for 900 miles. This problem is not a problem with constant acceleration. The formula $v^2=v_o^2+2ad$ is for constant acceleration, and is not applicable here.

 

[fresh_42]

Thanks Charles and SammyS.

@Ashley1nOnly What makes you think you will understand what 69 posts before didn't achieve, which btw. is still open?
Thread closed.