SOLUTION: Two ice skaters stand face to face and "push off" and travel directly away from each other. The boy has a velocity of 5 m/s and he weighs 740 N. The girl weighs 490 N. What is

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: Two ice skaters stand face to face and "push off" and travel directly away from each other. The boy has a velocity of 5 m/s and he weighs 740 N. The girl weighs 490 N. What is      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 460418: Two ice skaters stand face to face and "push off" and travel directly away from each other. The boy has a velocity of 5 m/s and he weighs 740 N. The girl weighs 490 N. What is the girl's velocity?
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Assuming no frictional losses, the total momentum within the system will remain unchanged, and it will remain zero (zero because we are accounting for velocities in different directions, not the actual speeds).

The masses of the boy and girl can be found by taking 740 N and 490 N and dividing each by g. Hence, we can find the momentum of each person:



The momentum of the girl is



The two momenta add up to zero so we can solve for v_girl:



(negative because the velocity is in the opposite direction of the boy's)

(Excuse my weird notation, but I decided not to divide 740, 490 by 9.81 simply because it is not needed and g will cancel out anyway. I just left it in there along with the units since the units have to be consistent.)