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- 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!