Problem Solving Strategies

7:59 AM

Hello @JohnRennie sir

@PrateekMourya hi

I am not able to understand in example 4.7 why does there is a condition that it may nit leave frustum

Yes

Let me draw a diagram ...

That's a cross section through the cone showing the ball.

The surface of the cone exerts a normal force N on the ball, and this force is at an angle θ to the horizontal where θ is equal to the cone angl. OK so far?

8:09 AM

Is it similar to banking of road where component of normsl balances centripetal and Wight

So at bottommost point it start circular motion and weigh is supported by normal component?

Yes

In fact it's exactly the same as a banked road.

Thanks without diagram i may not be able to point this out

8:26 AM

@JohnRennie Hi!

Are you free?

@YouKnowMe hi, yes I'm free

@JohnRennie Why do iron fillings assemble in this position?

If you look at each individual particle of iron in the filings you'll see they are shaped like needles i.e. long and thin.

When you put iron in a magnetic field that magnetic field induces a polarisation in the iron i.e. it temporarily magnetises the iron.

So each particle of iron becomes magnetised and behaves like a tiny bar magnet. That means it will align with the direction of the magnetic field in its vicinity.

That's what you are seeing. The needles of iron are lining up with the magnetic field lines from the bar magnet.

Why do all iron fillings not get accumulated at the poles?

The friction with the paper holds them in place. If you attempted this floating in space, e.g. aboard the International Space Station the filings would all stick to the ends of the magnet.

8:35 AM

:-o

@JohnRennie Thanks :-)

9:17 AM

If we start introducing iron filings to a bar magnet, will the pattern begin from the poles and slowly grow to the equatorial region as we bring more and more iron filings? Further, is the pattern limited by the amount of iron filings or in other words, will we cover the entire region around the magnet with iron filings if we have surplus of filings. Thanks. — Guru Vishnu Feb 18 at 10:57

1 hour later…

Annamalai Sriram

10:28 AM

@satan29 Actually I saw this question in discord server of OPHO.

2 hours later…

satan 29

12:26 PM

cool

5 hours later…

5:07 PM

Hello @JohnRennie sir

What you do when you are not able to identify whats confusing yiu

@PrateekMourya I'm not sure. Can you give me an example?

6:04 PM

I am facing problem in complex numbers but i am not able to find out in particular topics what is confusing me

And what are my weakness

Because i am not able to deduce methods to solve questions.

You mean you look at the problem and have no idea where to start?