Answer:
Approximately (downwards.)
Assumptions:
- the rocket started from rest;
- the gravitational acceleration is constantly
;
- there's no air resistance on the rocket and the two fragments.
- Both fragments traveled without horizontal velocity.
Explanation:
The upward speed of the rocket increases by . If the rocket started from rest, the vertical speed of the rocket should be equal to
.
The mass of the rocket (before it exploded) is 1500 kilograms. At 20 m/s, its momentum will be equal to .
What's the initial upward velocity, , of the lighter fragment?
The upward velocity of the lighter fragment is equal to once it reached its maximum height of
.
.
.
Mass of the two fragments:
- Lighter fragments:
.
- Heavier fragment:
.
Initial momentum of the lighter fragment:
.
If there's no air resistance, momentum shall conserve. The momentum of the lighter fragment, plus that of the heavier fragment, should be equal to that of the rocket before it exploded.
The initial momentum of the heavier fragment should thus be equal to the momentum of the two pieces, combined, minus the initial momentum of the lighter fragment.
.
Velocity of the heavier fragment:
.