The mass ratio of a rocket is defined to be the A) mass of the ...

[Mr. Wonderful]

The mass ratio of a rocket is defined to be the
 
  A) mass of the empty rocket without fuel divided by the mass of the payload
  B) mass of the fully fueled rocket divided by the mass of the rocket after the fuel is burned
  C) mass of the rocket after the fuel is burned divided by the mass of the fully fueled rocket
  D) mass of the fuel in the rocket divided by the mass of the rocket payload

Question 2

The excited state of a certain atom is 3.2 eV  0.21 eV.
 
  (a) What is the average lifetime of this state?
  (b) If the excited energy doubled (6.4 eV  0.21 eV) how would the lifetime be affected?

[nathang24]

Answer to Question 1

B

Answer to Question 2

(a) 1.6 fs
(b) unchanged, uncertainty still  0.21 eV