 #1
meghanflowers
 1
 0
 Homework Statement:

A rocket of mass m is launched straight up with thrust Fthrust.
Find an expression for the rocket's speed at height h if air resistance is neglected.
Express your answer in terms of the variables Fthrust , m , h , and appropriate constants.
 Relevant Equations:

vfs^2=vis^2+2Δs
a=F/m
I substituted 0 for vi, as the rocket is initially stopped.
I am looking for Vf.
So:
Vf^2=0+2asΔs
Vf^2=2asΔs
I then substituted a=Fthrust/m
So:
Vf^2=2(Fthrust/m)Δs
Δs at any given moment equals h so I substituted h for Δs.
Then took the square root of both sides.
Vf=sqrt(2h(Fthrust/m))
It says it is wrong, and that the correct answer includes the gravitational acceleration constant(g).
I am really stuck. Thanks for helping!
I am looking for Vf.
So:
Vf^2=0+2asΔs
Vf^2=2asΔs
I then substituted a=Fthrust/m
So:
Vf^2=2(Fthrust/m)Δs
Δs at any given moment equals h so I substituted h for Δs.
Then took the square root of both sides.
Vf=sqrt(2h(Fthrust/m))
It says it is wrong, and that the correct answer includes the gravitational acceleration constant(g).
I am really stuck. Thanks for helping!