# Questions received via chat interface

1. Why the magnetic field lines do not intersect
2. How contact force is related  with physical pendulum?

1. How contact force is related with physical pendulum?
A Physical Pendulum is any object suspended from a support, a knife edge in most cases but not located at its centre of gravity. Here the normal reaction offered by the knife edge is a contact force.

Have any other idea. Please feel free to post.

2. Why the magnetic field lines do not intersect?
Magnetic lines of force (also called magnetic field lines) are sooth curves in a magnetic field such that the tangent to it at any point gives the direction of magnetic field intensity at that point. So, if the magnetic field lines intersect anywhere, we can draw two tangents at the point of intersection indicating two directions of magnetic field at the same point WHICH IS NOT POSSIBLE
Is it clear.
Visitors are requested to post their answers and ideas.

3. CHAT TRANSCRIPT WITH A STUDENT (VISHNU)
Vishnu: when we bring a magnet near a Fe piece Fe moves from the initial position thus work is done.

me: ok

Vishnu: where the energy from?

me: There cannot be any net gain of energy or work

Vishnu: yes

me: Work done is ofcourse by spending energy

Vishnu: k

me: and here the work done is caused by the magnetic force

We can think a little more into it.

Vishnu: k

me: We are holding the magnet that is why the Fe moves towards you

Vishnu: yes

me: In moving it may be doing work against friction or against gravity

Vishnu: yes and for accelerating too

me: When the Fe is near the magnet, if we consider two points – one near the magnet and one near the Fe, we can explain this in terms of magnetic potential energy.
Vishnu: k

me: A decrease in Magnetic potential energy is responsible for the work

Vishnu: yeah

it means

when we attract lot of

stuff

the magnetic property reduces
9:46 PM
me: hmm

me: Means that the Fe is more stable when it is close to the magnet than when it is away

every system longs for stability

Vishnu: yes

me: The most stable position is the one with least PE

Vishnu: yeah

me: ?

Vishnu: Lot of them titled free energy

me:me: Anyone can post a video, BUT There is no FREE LUNCH
Vishnu: ha ha

me: So far there is no process detected which provides a gain of energy.

Vishnu: yeah
but i suppose there is

with destruction of mass

me: mass is also energy in store

Vishnu: ya

me: SO now we do not call mass and energy but together mass-energy
Vishnu: hmm

relativity

started

it

einstein rocks

me: tHINGS AND FACTS ARE THERE EVEN IF WE DON'T KNOW IT

Vishnu: ya
me: Gravity was there is there and will be there even if Newton didn't discover it

Vishnu: the best example
bye