How Should Momentum Conservation Be Applied in a Swing Ball Lab?

[DalekSec]

Homework Statement

The problem I am having, is my physics teacher will not explain a solution that he is having us use for a lab, and so I don't know what values to use for the equation.

The equation is to find the increase in momentum due to the work done by gravity. This is for a lab in which one metal ball berring is released from rest at a height 1.215 m above the ground. It swings downward on two strings, equal tension assumed, and strikes another ball at height .675 m above the ground, both ball are of equal mass. This ball then flies off the table and strikes the ground. The four reference frames are A: Both balls at rest, B: Ball on string was released and is about to hit the second ball at 3.255 m/s, C: second ball flies through the air and has an assumed air time of .371 sec., D: second ball is about to strike the ground. The problem is he wants us to use this equation, which I have no idea what to do with, and he won't tell us how to get these values.

I am a high school senior in AP Mechanics, and this is only a small portion of the lab. I just need to know what I am supposed to use for these values.

Homework Equations

%(delta)P= [PDt-(impulse due to gravity)(from time A to B)(in the vertical direction) -(impulse due to gravity)(from time C to D)(in the vertical direction)]/[(impulse due to gravity)(from A to B)(total),{i think that is what the t means},+ (impulse due to gravity)(from Cto D)(total)]

The Attempt at a Solution

There is no real attempted solution on this, I just need to know what some of these values are supposed to be, because he writes one thing and says another over the phone, and has confused me to know end.

 

[anathema]

Dear student,

I apologize for the confusion you are experiencing with your physics lab. it is important for me to help you understand the concepts and equations being used in your lab so that you can successfully complete it.

Firstly, let's break down the equation that your teacher has provided for you. It is a bit complicated, but I will explain it step by step.

%(delta)P= [PDt-(impulse due to gravity)(from time A to B)(in the vertical direction) -(impulse due to gravity)(from time C to D)(in the vertical direction)]/[(impulse due to gravity)(from A to B)(total),{i think that is what the t means},+ (impulse due to gravity)(from Cto D)(total)]

The symbol %(delta)P represents the change in momentum. This is the quantity that we are trying to calculate in this lab.

The first part of the equation, [PDt], represents the total impulse due to gravity from time A to time D. This means we are looking at the total change in momentum of the system from the initial time (when both balls are at rest) to the final time (when the second ball strikes the ground).

The next part of the equation, -(impulse due to gravity)(from time A to B)(in the vertical direction), represents the impulse due to gravity acting on the system from time A to time B. This is the time when the first ball is released and begins to swing downward on the strings.

Similarly, the next part, -(impulse due to gravity)(from time C to D)(in the vertical direction), represents the impulse due to gravity acting on the system from time C to time D. This is the time when the second ball is flying through the air and about to strike the ground.

Now, for the denominator, we have [(impulse due to gravity)(from A to B)(total),+ (impulse due to gravity)(from Cto D)(total)]. This represents the total impulse due to gravity acting on the system from time A to time B and from time C to time D.

Now, to find these values, we need to use the equation for impulse, which is given by FΔt = ΔP. In this case, since we are dealing with gravity, the force will be the weight of the objects (mg), and the time interval (Δt) will be

 

[thomate1]

As a scientist, it is important to have clear and thorough explanations in order to properly understand and conduct experiments. It is concerning that your physics teacher is not providing you with the necessary information to complete the lab and understand the equations being used. It is important to have a solid understanding of the concepts and equations being used in order to accurately analyze and interpret the results of the experiment. I would suggest discussing your concerns with your teacher and asking for a more thorough explanation of the equation and values being used. It is also important to ask for clarification on any discrepancies between written instructions and verbal instructions. Remember, as a scientist, it is important to have a clear understanding of the methods and data being used in order to draw accurate conclusions from experiments.