360/12 * 1/4 = 7.5
Odd Ball Interview Questions
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360/12 * 1/4 = 7.5
Yup seems easier when it's written down but it took me a few minutes to get it in the interview and they said very few people get it right
That's a good one most people I've asked think the 3.15 one is 0
I love brain teasers. MORE PLEASE
Q] Two clyinders, one rolls down the hill and the other is lubricated and slides down. They are both at the same height on a uniform slope. If released at the same time do they:
1) Arrive at the bottom at the same time
2) The rolling one wins
3) The sliding one wins
Q] Two clyinders, one rolls down the hill and the other is lubricated and slides down. They are both at the same height on a uniform slope. If released at the same time do they:
1) Arrive at the bottom at the same time
2) The rolling one wins
3) The sliding one wins
You need to brush up on your Physics
Considering the lack of information and clarification in the original question, they would arrive at the same time. Since you've given no indication as to the extent that your lubricant offsets the generated friction, we can only assume that friction is negligible. If the environment is frictionless, both states are under the same forces and will accelerate down the slope at the same rate.
I'd go for the sliding one to win. - Think about your bike wheel - it doesn't just start turning with no effort, you have to transfer some kinetic energy to the pedal somehow. Thus, with a rolling cylinder, there is less energy available to be kinetic energy from the cylinders velocity in the direction that is towards the bottom of the slope, as some of it is used up by the revolution on the cylinder.
Soldato
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The revolving cylinder doesn't use any energy in physics land. It's a closed system and any energy used in lifting one side of the cylinder is made up for by the other side falling. In physics land you could set an object spinning and it would never stop without friction or air resistance. Once you introduce those things, all bets are off as things get too complicated.
There is no lack of information, you understood it perfectly. All you need to know is in your post. GreatAUK got it.
Rolling:
GPE = Kinetic1 + Rotation
Sliding:
GPE = Kinetic2
=> Kinetic1 < Kinetic2
Therefore the sliding one gets to the bottom first.
This was a question from my university interviews.
s = ut + 0.5at^2 says otherwise, surely? The only way it could be otherwise is if the acceleration were different, which could only be due to friction or air resistance. If we assume they don't apply, which is reasonable for this sort of question, then surely they'll take the same length of time, rolling or not.
Besides, as said, the cylinder creates and loses GPE as it rolls, because as one side falls, using up GPE, the other rises, generating GPE.
Besides, as said, the cylinder creates and loses GPE as it rolls, because as one side falls, using up GPE, the other rises, generating GPE.
DONT QUESTION THE PHYSICS!
The acceleration is different! one has friction (It is required to cause the rotation) and therefore the net force is reduced. This is the other way of solving the problem.
I dont get your last statement. what rises? they are both rolling down a slope
The acceleration is different! one has friction (It is required to cause the rotation) and therefore the net force is reduced. This is the other way of solving the problem.
I dont get your last statement. what rises? they are both rolling down a slope
It did cross my mind that friction should exist for rotation, but in physics land, friction usually doesn't exist, so without your original question stating that the slope is not frictionless, it's a bit of a leap.
As for my last statement, as a wheel rolls one side rises as the other falls. In a closed frictionless system the wheel would roll forever as no energy is lost.
As for my last statement, as a wheel rolls one side rises as the other falls. In a closed frictionless system the wheel would roll forever as no energy is lost.
With the elephant, you surely would hold the elephant, stand on the scales, weigh you and the elephant. Then weigh yourself on your own and take away your weight from the joint weight which you had before. Then you have the weight of the elephant.
I read and learnt this on how to measure a TV somewhere on this forums.
I read and learnt this on how to measure a TV somewhere on this forums.
If you're saying the lubricated one experiences negligible friction and the rolling one experience some (non-negligible) friction, then yes the sliding one would win... Bit of an odd question though, as Vonhelmet said it needs slightly more info to give the 'correct' answer.
Sorry i still dont see what you're getting at. Yes it would, but thats not relevent to the question. As for the GPE if its of uniform density, a spinning object does not gain GPE as it spins (around an axis of symmetry)
I think we have gone a little off topic hurrr, sorry
^^He he^^