How Do You Calculate Change in Momentum Without Mass?

AI Thread Summary
To calculate the change in momentum without knowing the mass of the ball, focus on the concept of momentum per unit mass, which is equivalent to the velocity. The problem specifically asks for momentum per unit mass, so you can directly use the recorded velocity values from your experiment. The sign of the velocity is important and depends on your chosen direction for positive values; if the ball is falling downwards, it would typically be negative. Thus, the change in momentum per unit mass can be determined by analyzing the velocity data collected during the impacts. Understanding these principles will allow you to solve the problem effectively.
amanda.ka
Messages
46
Reaction score
0

Homework Statement


I did an experiment where I dropped a ball beneath a motion sensor and it recorded the vertical components of position vs time, velocity vs time, and acceleration vs time.
The question asks to determine the change in the ball's linear momentum (per until mass) during the 5 selected impacts with the ground. I know that the equation for linear momentum is p = (mass)(velocity) however the experiment did not say to weigh the ball so I do not have "m". How would I go about solving this? Also I know that momentum is a vector quantity so the sign is important. Does that mean my velocity values would be negative as the ball is falling towards the ground? Thanks in advance!

Homework Equations


p = mv

The Attempt at a Solution

 
Physics news on Phys.org
amanda.ka said:

Homework Statement


I did an experiment where I dropped a ball beneath a motion sensor and it recorded the vertical components of position vs time, velocity vs time, and acceleration vs time.
The question asks to determine the change in the ball's linear momentum (per until mass) during the 5 selected impacts with the ground. I know that the equation for linear momentum is p = (mass)(velocity) however the experiment did not say to weigh the ball so I do not have "m". How would I go about solving this?
Note that the problem didn't ask you for the momentum but the momentum per unit mass.

Also I know that momentum is a vector quantity so the sign is important. Does that mean my velocity values would be negative as the ball is falling towards the ground? Thanks in advance!
This depends on your sign convention. Which direction do you want to call the positive direction? If the ball's velocity is in that direction, it would be positive; if it's in the opposite direction, it would be negative.

Homework Equations


p = mv

The Attempt at a Solution

 
vela said:
Note that the problem didn't ask you for the momentum but the momentum per unit mass.

Does this mean that the linear momentum would just be equal to the velocity?
 
Yes, the momentum per unit mass is just the velocity.
 
  • Like
Likes amanda.ka
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Back
Top