posted by James .
Stuck in the middle of a frozen pond with only your physics book, you decide to put physics in action and throw the 9-kg book. If your mass is 45 kg and you throw the book at 10 m/s, how fast do you then slide across the ice? (Assume the absence of friction. Let the direction the ball is initially moving be the positive direction.)
The momentum of the book is m1*v1 in +ve x-direction. Since there is no external force in the horizontal direction, the linear momentum of the 'book and you' system will be conserved. Therefore you would have the same magnitude of momentum in the opposite direction. If your momentum is m2*v2 =>
m1*v1 = m2*v2
v2 = (m1*v1)/m2
v2 = 9*10/45 = 2 m/s
So you slide at 2m/s in -ve x direction
I think my book has a typo. It should say book, not ball.
Probably you and not your book. #Proud