Lab: Conservation of Momentum in One and Two Dimensions

Name ______Pd____

Lab Partners:______

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Lab: Conservation of Momentum in One and Two Dimensions

Purpose: To investigate graphically what the outcomes of collisions between steel balls of equal

mass in two dimensions will be.

Discussion: We have been studying conservation of momentum for collisions in one and two dimensions,

using calculations and drawingsas if the theories about such collisions really work. This lab

will investigate whether conservation of momentum of objects involved in elastic collisions

actually works by seeing whether the sum of vector momentums of two identical steel balls

after a collision is equal to the sum of their original momentums.

Procedure:

• Set up the launch ramp equipment as shown, clamping it securely to the table top. Mark the top of the ramp where you plan to release each impacting ball.

• Place the carbon paper (carbon side down) over your data collection sheet and tape if to the ground.

• Dangle the plumb line from beneath the target ball impact point at the end of your launch ramp to the ground and mark and label the START point on your data sheet.
• For each trial, first roll your impact ball down the ramp and allow it to hit the paper without hitting the target ball. Why do you want to do this?

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• Connect the start and impact point of the ball on the sheet to show the original momentum vector po
• Now roll the ball down the incline so it hits the target ball with a glancing (offset) collision.
• Connectthe start point and final landing points of the two balls with a line showing the vector momentums of each after the collision.
• Measure and label the angles between the original and final momentum vectors, and measure and label the distances representing the original as poandthe two final momentum vector lengths as pf1and pf2.
• Carefully move one of your final target momentum vectorsptwithout changing its direction or length and add it to you’re the other final impacting momentum vector pf, showing and labeling the resultant momentum vector aspR and measuring and recording the resultant length and angle measurement between the original and resultant momentum vectors. (See diagram below)

• Calculate the percent difference between your resultant momentum vector length and the original momentum vector length and record it on the original data sheet for that trial. Which one should you use as the truer value?

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• Calculate the percent differenc between your original momentum vector direction and your resultant direction as a measure of the angle of deviation out of 360o
• Each lab group member will have their owndata sheet, and include thatoriginal data sheet with their lab writeup.
• Fill in the data table below to summarize your results.
• Answer the questions within and at the end of the lab.

Data Table/Calculations:

Questions:

1. Why is it necessary to release the impacting ball from the same height each time?

2. What would be the impact on your data if you DON’T secure the paper? Be specific.

3. What are three reasons why your final resultant momentum vector was not exactly the same length or

pointed in the same direction as your initial momentum vector?

1. ______

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1. ______

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1. ______

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4. Qualitatively analyze the effect of one of your three sources of error, demonstrating clearly the impact

of the amount of error you propose was reasonably the cause of the error.

5. Quantitatively analyze the effect of one of your three sources of error, demonstrating clearly the impact

of the error you propose was reasonably the cause of the error.