<u>Answer:</u> The Fermi velocity of lead is 64.4 km/s.
<u>Explanation:</u>
To calculate the Fermi velocity, we use the equation:
where,
h = Planck's constant = 
= mass of electron = 
N = Number of atoms present in per volume of atom multiplied by number of electrons present in given atom = 
= Avogadro's number = 
(When the mass is in kilograms)
V = Volume = 
M = molecular weight of lead = 207.2 g/mol
Putting values in above equation, we get:
(Conversion factor: 1 km = 1000 m)
Hence, the Fermi velocity of lead is 64.4 km/s
<h2>The option a is most appropriate </h2>
Explanation:
The total pressure due to liquid column at any place is the sum of
( i ) pressure due to liquid column called hydrostatic pressure
( ii ) the pressure due to air column above the liquid column , which is called the static pressure
Thus total pressure is the sum of hydrostatic and static pressure .
Thus the option a is most appropriate
Answer:
False
Explanation:
Think of the electric potential in terms of potential energy. If you imagine a place with high elevation (A) and another one at sea level (B), a ball will roll from high potential to low potential (A-->B).
Everything in our universe wants to reach a lower state of energy if no external force is acted upon it. Every object tends to slow down (friction), a radioactive element dissipates energy (an unstable element releases energy to get to a stable state), water in the clouds comes down to the ground (rain experiencing difference in potential energy).
Electric potential is exactly the same, you just can't see it! It flows from higher voltage (which is a synonym for electric potential) to lower voltage.
Answer:
it's pray hoped this helped
Let say the two train cars are of masses 
and 
now if the speed of two cars are 
and 
then we can say that the momentum of two cars before they collide is given by
here two cars are moving in opposite direction so we can say that the net momentum is subtraction of two cars momentum.
Now since in these two car motion there is no external force on them while they collide
So the momentum of two cars are always conserved.
hence we can say that the final momentum of two cars will be same after collision as it is before collision
