let the distance of pillar is "r" from one end of the slab
So here net torque must be balance with respect to pillar to be in balanced state
So here we will have

here we know that
mg = 19600 N
Mg = 400,000 N
L = 20 m
from above equation we have



so pillar is at distance 10.098 m from one end of the slab
Answer:
The difference in the length of the bridge is 0.42 m.
Explanation:
Given that,
Length = 1000 m
Winter temperature = 0°C
Summer temperature = 40°C
Coefficient of thermal expansion 
We need to calculate the difference in the length of the bridge
Using formula of the difference in the length

Where,
= temperature difference
=Coefficient of thermal expansion
L= length
Put the value into the formula


Hence, The difference in the length of the bridge is 0.42 m.
Here you go it was too long to type
687 days
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1. Magnetic properties of a substance depends on the structure of its valence electrons. It has something to do with orbitals so I suggest you study about molecular geometry of a compound/substance firstIt's the way a substance's atoms fit together, being pulled and pushed from all sides equally. exists in metallic bonds <span>if a substance is said to be magnetic, it is simply attracted by a magnet. if it is paramagnetic, it is repelled by a magnet.
2.</span>The magnetic field will be perpendicular to the electric field and vice versa<span>
An electric field is the area which surrounds an electric charge within which it is capable of exerting a perceptible force on another electric charge.
A magnetic field is the area of force surrounding a magnetic pole, or a current flowing through a conductor, in which there is a magnetic flux. A magnetic field can be produced when an electric current is passed through an electric circuit wound in a helix or solenoid.
The relationship that exists between an electric field and a magnetic field is one of electromagnetic interaction as a consequence of associating elementary particles.
The electrostatic force between charged particles is an example of this relationship.</span>