Obviously, we can make rockets to go very fast, but what is a reasonable top spe

Question

Obviously, we can make rockets to go very fast, but what is a reasonable top speed? Assume that a rocket is fired from rest at a space station in deep space, where gravity is negligible. Assume that c = 3.00 × 108 m/s.

Part A

If the rocket ejects gas at a relative speed of 1500 m/s and you want the rocket's speed eventually to be 1.00×103 c, where c is the speed of light, what fraction of the initial mass of the rocket and fuel is not fuel?

Express your answer using three significant figures.

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Obviously, we can make rockets to go very fast, but what is a reasonable top speed? Assume that a rocket is fired from rest at a space station in deep space, where gravity is negligible. Assume that c = 3.00 × 108 m/s.

Part A

If the rocket ejects gas at a relative speed of 1500 m/s and you want the rocket's speed eventually to be 1.00×103 c, where c is the speed of light, what fraction of the initial mass of the rocket and fuel is not fuel?

Express your answer using three significant figures.

SubmitMy AnswersGive Up

Incorrect; Try Again; 4 attempts remaining

Explanation / Answer

Relevant formula: Vf = Vi + Vex*ln(Mi / Mf)

0.015 * 3e8m/s = 0 + 1500m/s * ln(Mi / Mf)

3000= ln(Mi / Mf)

1.9e130 = Mi / Mf

so a very, very, very tiny bit is not fuel (Mf is the final mass after all the fuels has been spent).

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