Final velocity, incomplete equation (answear included)

[bcoolplayer]

Homework Statement

A space vehicle traveling 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.

Homework Equations

The Attempt at a Solution

i got as far as this on the equation however I am 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]

i got as far as this on the equation however I am 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

 

[bcoolplayer]

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

 

[gneill]

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

 

[bcoolplayer]

im really stuck, i don't know please give me a hint

 

[gneill]

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

 

[bcoolplayer]

velocity

 

[gneill]

Which velocity?

 

[bcoolplayer]

the travling velocity

 

[gneill]

the travling velocity

Of what?

 

[bcoolplayer]

the space vehicle

 

[gneill]

the space vehicle

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

 

[bcoolplayer]

yees

 

[gneill]

yees

So then, what is V the velocity of?

 

[bcoolplayer]

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

 

[gneill]

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?

 

[bcoolplayer]

dllamberts principle

 

[gneill]

dllamberts principle

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