## What is gravity?

So I’ve been thinking about what gravity really is, I know it’s a rather weak force, but dominates the universe. Is there a possibilities that gravity is actually inter-molecular forces?

Asked Kevin

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## Direction of velocity and acceleration

Is it possible that the velocity and the acceleration of a body point in opposite directions? if yes then why?

if no then why?

Answer:

Yes. It is possible for the direction of acceleration to be opposite to the direction of velocity.

Acceleration is the rate of change of velocity. If velocity is increasing while moving in a straight line then the direction of acceleration is same as the direction of velocity.

It the velocity is decreasing whil travelling in a straight line then the direction of acceleration is opposite to the direction of velocity.

Example: When a stone is thrown vertically upwardsm its acceleration is downwards and velocity is upwards.

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## susceptibility

* harshal asks
The susceptibility of annealed iron at saturation is 5500.find its permeability at saturation*

* Ans: The absolute permeability, μ( = B/H) and the volume susceptibilityκ (= J/μ_{0}H), are related by the equation: μ* =

*μ*

_{0}(1 +

*κ*)

## CONDUCTING SLAB BETWEEN THE PLATES

How the value of capacitance change if we introduce conducting slab in between?

Sureshkumar kve

Capacitance increases as the distance between the plate reduces

## Change in resistance of a wire on stretching

A WIRE OF LENGTH L AND AREA OF CROSS SECTION A HAS A RESISTANCE R. IF THE WIRE IS STRACHED TO TWICE OF ITS LENGTH WHILE A REMAINS SAME , WHAT IS THE NEW RESISTANCE????

Answer:

We know that R = ρl/A

When the wire is **stretched**, there is no change in volume. So if length is doubled then volume will be halved so that volume is constant.

Therefore, the new resistance R’ = 4R

That is the resistance becomes four times its original value.

1. A WIRE OF LENGTH L AND AREA OF CROSS SECTION A HAS A RESISTANCE R. IF THE WIRE IS STRACHED TO TWICE OF ITS LENGTH WHILE A REMAINS SAME , WHAT IS THE NEW RESISTANCE????

## Why do we represent particle by a group of matter waves and not by single de Broglie wave

Why do we represent particle by a group of matter waves and not by single de Broglie wave?

## Problem from Kinematics

A particle moving with constant acceleration describes in the last second of its motion 9/25th of the total.if it starts from rest how long is the particle in motion and through what distance does it move if it describes 6 cm in first sec

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