The h Bar

Johan Liebert

12:03 AM

@ACuriousMind good morning! Yesterday I was serially upvoted but it hadn't been yet reversed. So thought to inform you.

JMac

12:27 AM

@JohanLiebert I got three upvotes in a row yesterday within 13 minutes.

on fairly random answers

Johan Liebert

3:18 AM

@JMac yes those were pretty old questions of mine so and they stopped getting upvote after 3 days of being asked. But suddenly 7 old post were upvoted in very short amount of time. I believe this is a case of serial upvoting.

Physics freak

5:15 AM

Hello everyone. I recently read this question physics.stackexchange.com/questions/16160/…. Now can someone tell me that if we have an object of mass say 10000kg and velocity 0.1m/s and a bullet of mass 0.01kg and velocity 1000m/s both have same area of cross section, would the damage on object(which is rigid and cannot move) they have been fired at still be same?

John Rennie

6:03 AM

@Physicsfreak hi. The two cases aren't really comparable because they would both do damage but in very different ways.

ACuriousMind

7:09 AM

@JohanLiebert please raise a custom mod flag on one of the up voted posts - that way, all mods can see it. Chat isn't the best channel for this

Physics freak

@JohnRennie Sir, since the kinetic energy of both is same they would travel equal distance before coming to rest so what are the other different ways damage would occur?

John Rennie

@Physicsfreak Suppose you're standing in front of the 10 tonne object moving at 0.1 m/s. When it hits you it will just push you out of the way and no harm will be done. The bullet will go straight through you instead of pushing you out of the way.

Physics freak

7:25 AM

@JohnRennie What if the 10 tonne mass is as small as a bulley

Bullet**

John Rennie

@Physicsfreak As long as it's only moving at 0.1m/s it will still just push you out of the way.

Imagine I poke you with the end of a stick at 0.1m/s. It would just push you away.

It you had yoru back to a cliff and couldn't move out of the way that would be different. In that case the stick would spear you at 0.1m/s, which would be a gruesome way to die! :-)

Physics freak

@JohnRennie Oh so deciding about the impact of collision merely based on values of momentum and kinetic energy is not useful

John Rennie

7:41 AM

Yes

Physics freak

@JohnRennie @JohnRennie That was an interesting ans. Thanks sir

Johan Liebert

@ACuriousMind done.

John Rennie

@Physicsfreak you're welcome :-)

Johan Liebert

9:01 AM

34

Q: Does gravity increase the closer to the core you get?

Or does the mantle and crust above you counteract the increase at one point and it actually decreases?

John Rennie

9:21 AM

@JohanLiebert I think that's been asked here before.

Johan Liebert

9:51 AM

@JohnRennie I found this question on earth science SE. One thing that surprised me was that many people in the comment were surprised by the Shell Theorem.

John Rennie

Non-physicists eh? You have to feel sorry for them :-)

Johan Liebert

@JohnRennie yes. The traffic comes from Stack Overflow.

11:10 AM

12:37 PM

I’m not able to find the flag option for comments in mobile site.

PM 2Ring

@Knight There isn't one. You have to switch to the full site view for that.

Knight

@PM2Ring I’m not in situation to use full desktop site, if I give you the link may you please flag it as the commenter is not stopping his comments.

PM 2Ring

@Knight There's a link to the full site view at the bottom of the page. You can use it on a phone.

But you can give me the link if you want to.

Knight

12:56 PM

@PM2Ring Thank you so much sir. Here is the link

@PM2Ring Sir I was waiting for you from two days, we need you here:

-1

Q: How can a user participate on Physics Stack exchange properly if the user have some problems with English Language

We all know users on our PSE come from all parts of the world and it seems obvious that if someone is using the internet he/she must be writing and understanding English properly. But in some countries the web pages are purely in regional language and therefore users from those regions (of course...

discussion support language

PM 2Ring

@Knight I'm sorry, I don't agree that those comments are spam or rude.

@Knight Yes, I read that question yesterday, and I know who you're talking about.

Knight

@PM2Ring I can explain my points if you wish. Where I’m wrong in my answer.

PM 2Ring

@Knight If there are wrong things in your answer you should fix it. It might not seem like it to you, but David is trying to assist you in fixing that answer.

Knight

@PM2Ring Sir I fixed t today, that clarification is added today only.

@PM2Ring He is spamming because he is understanding something else from my answer and showing no signs of learning about why wrote it and keeps on commenting “you’re wrong”.

PM 2Ring

1:12 PM

@Knight The term "spam" on Stack Exchange sites means commercial spam: posts intended to obtain some kind of financial advantage, like advertising. Don't use spam flags for posts that aren't commercial spam. Actual spamming carries heavy penalties.

@Knight The OP is asking about the position vector. They aren't interested in that r radius vector that your answer talks about.

Knight

1:26 PM

@PM2Ring Sir I have explained in my answer what position vector actually mean when we consider rotational motion. Wasn’t it clear?

PM 2Ring

@Knight Yes, that's clear now. But most of your answer is talking about r, and that's not really relevant to the OP's question.

I have to admit that I don't fully understand David's most recent comment: physics.stackexchange.com/questions/530105/…

Transcript for