Answer:
The number of vacancies per cubic meter is 1.18 X 10²⁴ m⁻³
Explanation:
![N_v = N*e[^{-\frac{Q_v}{KT}}] = \frac{N_A*\rho _F_e}{A_F_e}e[^-\frac{Q_v}{KT}}]](https://tex.z-dn.net/?f=N_v%20%3D%20N%2Ae%5B%5E%7B-%5Cfrac%7BQ_v%7D%7BKT%7D%7D%5D%20%3D%20%5Cfrac%7BN_A%2A%5Crho%20_F_e%7D%7BA_F_e%7De%5B%5E-%5Cfrac%7BQ_v%7D%7BKT%7D%7D%5D)
where;
N
is the number of atoms in iron = 6.022 X 10²³ atoms/mol
ρFe is the density of iron = 7.65 g/cm3
AFe is the atomic weight of iron = 55.85 g/mol
Qv is the energy vacancy formation = 1.08 eV/atom
K is Boltzmann constant = 8.62 X 10⁻⁶ k⁻¹
T is the temperature = 850 °C = 1123 k
Substituting these values in the above equation, gives
![N_v = \frac{6.022 X 10^{23}*7.65}{55.85}e[^-\frac{1.08}{8.62 X10^{-5}*1123}}]\\\\N_v = 8.2486X10^{22}*e^{(-11.1567)}\\\\N_v = 8.2486X10^{22}*1.4279 X 10^{-5}\\\\N_v = 1.18 X 10^{18}cm^{-3} = 1.18 X 10^{24}m^{-3}](https://tex.z-dn.net/?f=N_v%20%3D%20%5Cfrac%7B6.022%20X%2010%5E%7B23%7D%2A7.65%7D%7B55.85%7De%5B%5E-%5Cfrac%7B1.08%7D%7B8.62%20X10%5E%7B-5%7D%2A1123%7D%7D%5D%5C%5C%5C%5CN_v%20%3D%208.2486X10%5E%7B22%7D%2Ae%5E%7B%28-11.1567%29%7D%5C%5C%5C%5CN_v%20%3D%208.2486X10%5E%7B22%7D%2A1.4279%20X%2010%5E%7B-5%7D%5C%5C%5C%5CN_v%20%3D%201.18%20X%2010%5E%7B18%7Dcm%5E%7B-3%7D%20%3D%201.18%20X%2010%5E%7B24%7Dm%5E%7B-3%7D)
Therefore, the number of vacancies per cubic meter is 1.18 X 10²⁴ m⁻³
The coefficient of static friction is 0.357 and the coefficient of kinetic friction is 0.265.
Explanation:
Coefficient of static friction is defined as the proportionality constant for the frictional force between the crate and floor for starting the motion of crate and normal force acting on the crate. As the normal force of the crate is equal to the influence of acceleration due to gravity acting on the mass of the crate, the frictional force for static friction coefficient will be the force applied to move the crate.
Thus, 
Since, the static friction force is 70 N, the normal force is equal to 
So normal force is 196 N and static force is 70 N, and the ratio of static friction force to the normal force will give the coefficient of static friction.

Similarly, the coefficient of kinetic friction can be determined from the ratio of kinetic friction force to normal force. Here the kinetic friction force will be equal to the force applied on the crate to keep it moving.

Thus, the coefficient of static friction is 0.357 and the coefficient of kinetic friction is 0.265.
Answer:

Explanation:
We are given that a parallel- plate capacitor is charged to a potential difference V and then disconnected from the voltage source.
1 m =100 cm
Surface area =S=


We have to find the charge Q on the positive plates of the capacitor.
V=Initial voltage between plates
d=Initial distance between plates
Initial Capacitance of capacitor

Capacitance of capacitor after moving plates


Potential difference between plates after moving








Hence, the charge on positive plate of capacitor=
I think the correct answer from the choices listed above is option A. In this experiment, sunlight is an independent variable. It is the variable that cannot be changed James no matter what. Hope this answers the question. Have a nice day.
In elastic
collision, both the kinetic energy and momentum are conserved. Conservation
means that both the kinetic energy and momentum will have the same values
before and after elastic collision.
<span>As the
object A has low mass than object B. Hence upon collision, object B moves
forward, while object A will move backward. So option "C" is correct. </span>