This question is not directly from a text book. The originalquestion stems from

Question

This question is not directly from a text book. The originalquestion stems from Physics For Scientists and Engineers withModern Physics. Our teacher has the class complete homeworkproblems online using webassign, so the numbers are not thesame. I need help completing the first portion of the problem,part a. The teacher did not give me a clear explanation of whatexhaust speed was. I know the equation, but I don't know how to useit. I keep getting the question wrong. I think I need to useanother equation from a previous chapter but am unsure which touse. Here is the question:

Model rocket engines are sized by thrust, thrust duration, andtotal impulse, among other characteristics. A size C5 model rocketengine has an average thrust of 5.26 N, a fuel mass of 12.7 g, andan initial mass of 25.5 g. The duration of its burn is 1.90 s.(a)What is the average exhaust speed of the engine? (b)If thisengine is placed in a rocket body of mass 56.0 g, and if the rocket is fired in outer space,what is the final velocity of the rocket? Assume the fuel burns ata constant rate.

Explanation / Answer

height  travelled by the rocket                 h= at^2 / 2     a = F / m        F = force due tothrust        m = mass of therocket          t = time ofexhaust           total potential energy gained by the rocket = mgh if the engine is inserted into a rocket of mass =M     kinetic energy gained by the rocket aftercomplete exhaust when projectd in outer space                   Mv^2 / 2 = mgh                           finalvelocity of rocket in outer space                      v = 2mhg / M

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