A 140 kg rocket is moving radially outward from the earth at an altitude of 200 km above the surface with a velocity of 3.5 km/sec. At this point, its final stage engine shuts off.(adsbygoogle = window.adsbygoogle || []).push({});

a)Ignoring any minor air resistance, what is the rocket's velocity 1000km above the surface of the earth?

b) What is the maximum height of the rocket above the earth's surface (using the initial rocket mass of 140 kg)?

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Part a was easy. Using the escape velocity equation, I did v=sqrt(2G*M/R)

where G is the 6.67E-11 constant

M is mass of earth

and R is radius of earth plus 100,000m

I get answer of 108,240,434m/s

b) This is where I get stuck.

Using same equation

V=3.5km/sec=3500m/sec

G=6.67E-11

M=5.98E24kg

I solve for R, but its not working. I thought I'd take the R subtract earth radius from that, but its not working either. :(

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# Homework Help: Gravitation: Rocket's Velocity

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