# Final velocity, incomplete equation (answear included)

## Homework Statement

A space vehicle travelling at a velocity of 1200ms -1 separates by a controlled explosion into two sections of mass 865kg and 2010 kg. The two parts carry on in the same direction with the heavier rear section moving 120 ms -1 slower than the lighter front section. Determine the final velocity of each section.

## The Attempt at a Solution

i got as far as this on the equation however im stuck
(865+2010)*1200=865*V+(V-120)*2010=2875*…

we have been told that V=1284m/s
and heavier body velocity=1164m/s

gneill
Mentor
i got as far as this on the equation however im stuck
(865+2010)*1200=865*V+(V-120)*2010=2875*…

we have been told that V=1284m/s
and heavier body velocity=1164m/s

Well, you're almost there. You've got an equation that can be solved for V:

(865+2010)*1200=865*V+(V-120)*2010

ok that good 2 know, and where 2 go from here

gneill
Mentor
Ask yourself what V represents (after all, you wrote the equation!). Compare with what the problem is asking you to find out.

im realy stuck, i dont know please give me a hint

gneill
Mentor
Go back over your derivation of the equation. What was V for?

velocity

gneill
Mentor
Which velocity?

the travling velocity

gneill
Mentor
the travling velocity

Of what?

the space vehicle

gneill
Mentor
the space vehicle

Surely that's what the "1200" is on the left hand side of the equation?

yees

gneill
Mentor
yees

So then, what is V the velocity of?

i aint got a clue, is it for the heavier body velocity

gneill
Mentor
You need to be sure if you are to understand how to do these sorts of problems.

What physical law allowed you to write the equation in the first place?

dllamberts principle

gneill
Mentor
dllamberts principle

Not quite. There's a particular conservation law involved here.