- #1

Simka

- 1

- 0

This is what i managed to do:

rocket's speed at any moment t (with respect to the ground) is

**a*t**

gass's speed at any moment t (with respect to the ground) is

**u-a*t**

Mass of rocket at any time t is

**m-mu*t**

Mass of fuel that is burned is

**mu*t**

rocket's mass multiplied by it's speed and gass's mass multiplied by its speed are equal, so

**(m-mu*t)*a*t=mu*t*(u-a*t)**

and i get that

**m*a*t=mu*t*u**

**mu=(m*a)/u**=6.53 kg/s

but... I was given 4 answers (5.9kg/s 9.8kg/s 39.2kg/s 19.8kg/s) and mine is wrong...

Any ideas anyone?