Definition of pound force

  • Thread starter Thread starter Roady
  • Start date Start date
AI Thread Summary
The discussion revolves around the concept of pound force (lbf) and its application in physics, specifically in accelerating a mass of 32 pounds (lbm). Participants express frustration over the lack of practical demonstrations showing 1 lbf moving 32 lbm at a specific acceleration. The conversation highlights the complexities of unit conversions in the U.S. customary system, emphasizing that the formula F=ma is not straightforward due to the system's incoherence. One contributor points out that understanding the relationship between force, mass, and acceleration requires a grasp of unit conversion factors. The thread ultimately emphasizes the importance of guiding individuals toward understanding rather than simply providing answers.
Roady
Messages
9
Reaction score
1
Homework Statement
prove by physical demonstaration1lbf accelerates 32lbm @ 1ft/s^2. Is there a pic of a classroom experiment proving this?
Relevant Equations
def 1lbf=32lbm*1ft/s^2
I can divide the #'s out, but so what. I want to see 1lbf move 32lbm.
 
Physics news on Phys.org
Roady said:
I want to see 1lbf move 32lbm.
Are you trying to convince yourself? Or a third party doubter? How direct does the proof need to be?
 
Roady said:
Does it matter? Can you answer the question?
The direct answer is that I know of no picture or video demonstrating a 32 pound weight being accelerated at 1 foot per second per second by a 1 pound force.

Given the available coefficients of friction, the best demonstration that I can think of would involve something like a pendulum bob on a long wire.
Roady said:
Do you know of a friggn experiment? I'm getting the most inane answers from respondants here; another:can you see your mistake?
Did I speak of your mistake or even imply that you'd made one? In this thread you have not made any mistakes. Up until now, you'd only asked a question.

Roady said:
Duh, if I could I wouldn't ask for help.
Here at physicsforums.com we help people help themselves. That means guiding people to an understanding. Not simply answering questions.
Roady said:
1lbf=m*g, what is that mass is another angle? 1lbf=32lbm*1f/s^2=1lbm*32/s^2, but this product is 32lbm*ft/s^2, so that has to account for something if it's not a pound force.
It sounds like you are trying to argue rather than to understand. And since you have another thread open on this same subject, I will stop responding here.

I will say that ##F=ma## only works in coherent systems of units. More generally the formula is ##F=kma## where ##k## is a unit conversion factor. The U.S. customary system is not coherent. In the U.S. system with pounds force, pounds mass and feet per second squared, ##F = \frac{1}{32}ma##
 
Last edited:
  • Agree
Likes SammyS
Thread is closed temporarily for Moderation.
 
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