physics
posted by samm .
A firecracker in a coconut blows the coconut into three pieces. Two pieces of equal mass fly off south and west, perpendicular to each other, at 21m/s . The third piece has twice the mass as the other two.
What is the speed of the third piece?
What is the direction of the third piece?

I would use conservation of momentum in the S and west direction.
S direction
M*21S+2M*v S=0
so v in the South direction is 10.5
so the same in th eEast direction
v in the East Direction
V=10.5 E
angle= arctan 10.5/10.5 or NE at velocity 10.5*sqrt2