course phy 241
On the university physics only part of this lab, I am having trouble with the following:&&&Based on this result and on the mass ratio determined in the first setup, what is the vertical velocity of the first ball immediately after collision? Note that vertical momentum is conserved, and that since immediately before collision nothing was moving in the vertical direction, the total vertical momentum is zero immediately before collision.&&&&&
If mv+m2v2 for the before collision is equal to zero This is the case for vertical motion only
and the momentum is conserved wouldn't that mean that it has to be 0 after collision as well the after-collision momentum in the vertical direction is indeed zero
. This does not make sense to me. I thought maybe I could figure this out by using the same technique as the first taking the slope and relating it to the rise and run of the velocity, using a^2+b^2=c^2, and c representing the velocity found from the program, a being the horizontal component and b being the vertical component. "
You would use this to find the magnitude of a vector from its components, but you wouldn't use it in analyzing just the y momentum, which is only a single component.
The preceding instruction was also important here. The two instructions read:
Based on the slope of the initial after-collision path of the second ball and its velocity, as determined in the second setup, what is the vertical component of the second ball's immediate after-collision velocity?
Based on this result and on the mass ratio determined in the first setup, what is the vertical velocity of the first ball immediately after collision? Note that vertical momentum is conserved, and that since immediately before collision nothing was moving in the vertical direction, the total vertical momentum is zero immediately before collision.
Presumably you have determined the vertical component of the second ball's after-collision velocity, and you know the ratio of the masses of the two balls.
Immediately before collision the total vertical momentum is zero.
After collision the total vertical momentum is m1 * v1_y' + m2 * v2_y', where the ' indicates velocity after collision and the subscript y denotes vertical components.
So m1 * v1_y' + m2 * v2_y' = 0.
If you know m2 / m1 and v2_y' you can solve for v1_y'.