<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
A.
Kinematics is independent of mass, in most cases.
Answer:
245.45km in a direction 21.45° west of north from city A
Explanation:
Let's place the origin of a coordinate system at city A.
The final position of the airplane is given by:
rf = ra + rb + rc where ra, rb and rc are the vectors of the relative displacements the airplane has made. If we separate this equation into its x and y coordinates:
rfX = raX+ rbX + rcX = 175*cos(30)-150*sin(20)-190 = -89.75km
rfY = raY + rbY + rcT = 175*sin(30)+150*cos(20) = 228.45km
The module of this position is:

And the angle measure from the y-axis is:

So the answer is 245.45km in a direction 21.45° west of north from city A
Explanation:
Food chain is linear sequence of the organisms through which the nutrients and the energy pass as one organism eats the another.
<u>If one species in the food chain ceases to exist, the other members in rest of chain could cease to exist too or may increase in population which can affect other food chains. (Breaking of food chain).</u>
This is because the animals in the food chain are dependent on the nutrient present in the another.
For example in the food chain,
Grass ---- Deer ------ Lion
If all deer extinct, the lion will die as they will have nothing to feed on and the population of grass increases.
Answer:
To find the volume of a rectangular object, measure the length, width and height. Multiply the length times the width and multiply the result by the height. The result is the volume. Give the result in cubic units, such as cubic centimeters.
Explanation: