My profesor gave us this (I think) impossible problem to do.

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In summary, the conversation is discussing a problem involving a ball being rolled on a level floor and making 15 revolutions. The question asks for the diameter of the ball, but there is not enough information to answer the other questions regarding angular acceleration, linear acceleration, and final velocity when stopped. There is confusion about what the initial velocity should be assumed to be and whether the answers should be 0. The conversation ends with the conclusion that the problem is poorly worded and there is likely missing information.
  • #1
thrillhouse
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She may want us to assume something but I'm not sure and can't ask her for a while. There just isn't enough info I think. here it is.

A ball is rolled on level floor a distance of 3.5m to another person. The ball made 15 revolutions.

a) asked for diameter of the ball which is easy and I got that only.

HERE WE GO NOW
if the rolling time is 10 seconds...

b)what is angular acceleration?
c)what is linear acceleration?
d)what is final velocity when it is stopped?


I see no way to answer b-d without more info. Does anyone have any idea what she wanted us to assume? This is all the info she gave. I guess D could be 0 but I'm not sure if that's what she's looking for.

thanks
 
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  • #2
Was the ball stopped at 0s?
Because if it was stopped at the start and stopped at the end it should tell you something about the acceleration.
 
  • #3
it is pushed by someone and stopped by the person on the other end of that 3.5m. So since it was rolled by someone, I would assume initial velocity is 0 until it is rolled.
 
  • #4
thrillhouse said:
d)what is final velocity when it is stopped?

?

If the answer isn't 0, this is a very poorly worded question. If it is, it's just a poor question. As for the rest, the average acceleration (assuming that's what you want) is defined the same way as the average velocity, which is total distance covered (or total change in position) divided by total time.
 
  • #5
^

I don't know about that... ANGULAR ACCELERATION is described as w(omega) w2-w1/t2-t1

Is w supposed to be the distance?

And I still have no idea on the linear acceleration.
maybe V-Vinitial/t ?
 
  • #6
w is angular velocity. Does this help?
 
  • #7
Well, so how could I answer b,c,d? I'm looking for an answer if you don't mind, not just some help.

I want to discuss this with the professor when I get the chance. I even asked the tutor at school and he's says he's in a huge disagreement with her over this problem.
 
  • #8
thrillhouse said:
A ball is rolled on level floor a distance of 3.5m to another person.
Are you sure about it being a level floor? If the floor were slanted, this problem would make more sense. In that case you'd have linear and angular acceleration and a final velocity to calculate.
 
  • #9
Yes its level. I guess if you could explain it otherwise, she'd accept it.

How would you explain all 3 of those answers are 0?
 
  • #10
The answers are supposed to be 0? In that case, I think they want you to assume the ball is at rest at the beginning and end, which means neither its angular velocity or linear velocity change, and the average acceleration is 0 for both. The last question makes me angry, and I would refuse to answer it.
 
  • #11
thrillhouse said:
How would you explain all 3 of those answers are 0?
As StatusX said, the way this problem is worded the answers are zero.

Assuming the ball rolls without slipping, its speed after leaving the first person's touch is constant until it reaches the other person. Acceleration (while it's rolling) = 0.
 
  • #12
But wouldn't acceleration be decceleration because it would slow down as it goes?

But that's weird because as its pushed, the acceleration would have to rise, but it will slow down eventually so its decelerating.

This problem sucks.
 
  • #13
Go with your initial instincts. For whatever reason, you do not have all the information about the problem. Nobody here has decuced the missing information yet, and it is very unlikely they will.
 
  • #14
thrillhouse said:
But wouldn't acceleration be decceleration because it would slow down as it goes?

But that's weird because as its pushed, the acceleration would have to rise, but it will slow down eventually so its decelerating.

This problem sucks.

assuming ideal conditions then you can neglect friction and what not. which is most likely the nature of this problem.

as i see it, like previously stated, all the answers are zero.
 
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Related to My profesor gave us this (I think) impossible problem to do.

1. Why do professors give seemingly impossible problems to solve?

Professors often assign difficult problems to challenge students and to encourage critical thinking and problem-solving skills. These types of problems also help students develop perseverance and resilience when faced with challenging tasks.

2. How can I approach an impossible problem given by my professor?

When faced with a difficult problem, it is important to break it down into smaller, more manageable parts. Start by identifying the key concepts and variables involved, and then work through each step methodically. It may also be helpful to seek guidance from classmates or the professor if you are stuck.

3. What if I can't solve the problem my professor gave me?

It is important to remember that not all problems are meant to have a solution. Some problems are used to challenge our thinking and to push us beyond our comfort zones. If you are unable to solve the problem, reflect on the process and what you have learned from attempting to solve it.

4. Can I ask my professor for help with an impossible problem?

Yes, it is acceptable to seek guidance from your professor when faced with a challenging problem. However, make sure to first put in effort and attempt to solve the problem on your own. This will show your professor that you are actively engaged in the learning process.

5. How can I use the experience of solving an impossible problem in my future career?

The ability to tackle difficult and complex problems is a valuable skill in any profession. The experience of working through an impossible problem can help you develop critical thinking, problem-solving, and analytical skills that will be useful in various aspects of your career.

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