Originally posted by David113
I would say that when the total momentum of the system ball+earth is conserved. When the ball swings to the left, the earth moves (very slowly) to the right, reaching maximum speed when the ball stops at the leftmost point. When the ball starts moving to the right again, the earth's speed changes accordingly. In short, the momentum is conserved IN A CLOSED SYSTEM. But the ball isn't a closed system - it is attached to the earth.
I have trouble coming up with ideas like " the earth moves, because of the ball" The concept is simple, yet it is so displaced from day to day experience that it totally escapes my thought process! i guess the key to physics is to live within your mind, not within your world?
How long do you suppose it took Newton to conceptualize the earths momentum changing as a result of pendulum?
And, If the earths momentum changes as a result of the ball swinging does the momentum of the galaxy, universe...ect. change?
well thanks for the help