(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A rocket with mass 60 x 10^{3}kg (25 % of it is "empty mass"). The rocket burns the fuel at rate 250 kg/s and expel the gas at relative speed 1.6 km/s. Find the force experienced by the rocket and the time until the force equals to zero

2. Relevant equations

Δp = F.Δt

p = mv

W = mg

3. The attempt at a solution

I am not sure what is the meaning of "empty mass". Is it the mass of rocket without fuel?

This is my attempt:

Force experienced by rocket

= Δp / Δt

= Δ(mv) / Δt

= v . Δm / Δt

= 1.6 x 10^{3}x 250

= 4 x 10^{5}N

Is that correct?

For the time until the force ceases:

Assume empty mass means the mass of rocket without fuel, so the mass of fuel = 75 % of 60 x 10^{3}kg = 45,000 kg

Time = 45,000 / 250 = 180 s ---> this means that the rocket accelerates for only 3 minutes???

Thanks

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# Homework Help: Force on rocket

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