Work and Energy TBR Phase I Passage I Question 2

[dartmed]

Ok, the questions states how much would the potential energy of the television change if a 3 m ramp were used to get it up to the instead of a 2 m ramp?

I figured out the answer using intuition, but if the question ask by how MUCH PE changes if we used two different ramps, shouldn't it just be 0? Because PE is path independent?

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[chiddler]

If the height is the same, then mgh's should be equal. Another way of writing this is mgdsin(theta). So if the angles are the same, then the 3m ramp will go higher.

 

[dartmed]

If the height is the same, then mgh's should be equal. Another way of writing this is mgdsin(theta). So if the angles are the same, then the 3m ramp will go higher.

That's true, but what really frustrated was that the answer said delta PE was 1000J even though the height is the same. I guess I have a problem with how they phrased it.

 

[milski]

The only explanation I have is that that the ramp is 2 or 3 m high, not 2 or 3 m long. Do they say that the TV is 100 kg?

 

[MedPR]

Ok, the questions states how much would the potential energy of the television change if a 3 m ramp were used to get it up to the instead of a 2 m ramp?

I figured out the answer using intuition, but if the question ask by how MUCH PE changes if we used two different ramps, shouldn't it just be 0? Because PE is path independent?

That's true, but what really frustrated was that the answer said delta PE was 1000J even though the height is the same. I guess I have a problem with how they phrased it.

I know exactly what problem you're talking about because I had the same gripe with it. Are you going back to the beginning of TBR? Or have you just recently started studying? Your responses (very good ones) on other threads led me to believe that you were either nearing the end of studying or you had already recently finished your MCAT.

Had this not been a multiple choice question, I would've gotten it wrong because I would've said 0 as well.

The only explanation I have is that that the ramp is 2 or 3 m high, not 2 or 3 m long. Do they say that the TV is 100 kg?

I believe the TV is 50kg and the final height is 2m. Regardless of what the values are, both situations (either ramp) have the same final height starting from h=0. The answer is actually asking "What is the PE when the ramp is changed from 2m long to 3m long?" And not "What is the difference in PE when the ramp is changed to a 3m ramp?". The answer to the first question is the correct answer (according to TBR), and the answer to the second question should be 0, since the h is the same for both ramps.

 

[milski]

I believe the TV is 50kg and the final height is 2m. Regardless of what the values are, both situations (either ramp) have the same final height starting from h=0. The answer is actually asking "What is the PE when the ramp is changed from 2m long to 3m long?" And not "What is the difference in PE when the ramp is changed to a 3m ramp?". The answer to the first question is the correct answer (according to TBR), and the answer to the second question should be 0, since the h is the same for both ramps.

Ok, that makes sense, I agree with your conclusions.

Questions like this have a good potential for confusion since most of the time when talking about PE we're really talking about change in PE (or using an arbitrary 0, which is the same).

 

[MedPR]

Ok, that makes sense, I agree with your conclusions.

Questions like this have a good potential for confusion since most of the time when talking about PE we're really talking about change in PE (or using an arbitrary 0, which is the same).

Yea, it would suck if that question had 0 as one of the answer choices. There'd be no way for you to know which one they want

 

[dartmed]

I know exactly what problem you're talking about because I had the same gripe with it. Are you going back to the beginning of TBR? Or have you just recently started studying? Your responses (very good ones) on other threads led me to believe that you were either nearing the end of studying or you had already recently finished your MCAT.

Had this not been a multiple choice question, I would've gotten it wrong because I would've said 0 as well.



I believe the TV is 50kg and the final height is 2m. Regardless of what the values are, both situations (either ramp) have the same final height starting from h=0. The answer is actually asking "What is the PE when the ramp is changed from 2m long to 3m long?" And not "What is the difference in PE when the ramp is changed to a 3m ramp?". The answer to the first question is the correct answer (according to TBR), and the answer to the second question should be 0, since the h is the same for both ramps.

Thanks for the help, MedPR. Glad to see that I am not the only one that had a difficult time with the question.

I have been switching materials back and forth to stay more focused (weird trait of mine..lol). I read through all the chapters first, did some 1001 questions, some TPRH Workbook, and now I am wrapping-up Phase I/reviewing my previous answers once again. I am trying to finish the TPR Workbook, Phase I, and 1001 questions of all the content by the end of the month...hopefully, procrastination won't get the better of me.

It's my first time taking the test...hopefully my only time. Lol.

How far are you, if I may ask?

 

[MedPR]

Thanks for the help, MedPR. Glad to see that I am not the only one that had a difficult time with the question.

I have been switching materials back and forth to stay more focused (weird trait of mine..lol). I read through all the chapters first, did some 1001 questions, some TPRH Workbook, and now I am wrapping-up Phase I/reviewing my previous answers once again. I am trying to finish the TPR Workbook, Phase I, and 1001 questions of all the content by the end of the month...hopefully, procrastination won't get the better of me.

It's my first time taking the test...hopefully my only time. Lol.

How far are you, if I may ask?

I'm on day 28 or 29 or something. If you're following SN2ed's schedule, I'm caught up on Gen chem and physics, a day ahead on Bio (easiest thing for me to read at work and actually grasp concepts) and I'm currently reading Chapter 5 of organic. It's the carbonyl chapter and it is a monster (~50 pages).