- #1
Tj Nelson
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Homework Statement
A rocket with an initial mass of 60,000kg ignites its engines and burns fuel at a rate of 300 kg/s with an exhaust velocity of 2220 m/s. How long after the engines start does the rocket lift off the ground?
Homework Equations
From Newton's second law
F = Ma this equation can be derived
M(dv/dt) = Fext + u(dm/dt)
The Attempt at a Solution
I think the solution is fairly simple. What I did is divide by m, Fext = mg, and integrated it to get
ΔV = uln(mi/mf) - gΔt. But we don't know what the velocity of the rocket...