Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that the friction force on two boxes is given as



Now we know by Newton's II law

so we have




Part b)
For block B we know that net force on it will push it forward with same acceleration so we have




Part c)
If Alex push from other side then also the acceleration will be same
So for box B we can say that Net force is given as




Answer:
microwave, visible light, and radio waves.
Explanation:
Answer:

Explanation:
Let consider that pipe is a horizontal cylinder. The Nusselt number is equal to:
, for
.
Where
is the Rayleigh number associated with the cylinder.
The Rayleigh number is:

By assuming that air behaves ideally, the coefficient of volume expansion is:



The cinematic and dynamic viscosities, thermal conductivity and isobaric specific heat of air at 10 °C and 1 atm are:




The Prandtl number is:



Likewise, the Rayleigh number is:


Finally, the Nusselt number is:
![Nu = \left\{0.6+\frac{0.387\cdot (12.486\times 10^{6})^{\frac{1}{6} }}{\left[1 + \left(\frac{0.559}{0.733}\right)^{\frac{9}{16} }\right]^{\frac{8}{27} }} \right\}^{2}](https://tex.z-dn.net/?f=Nu%20%3D%20%5Cleft%5C%7B0.6%2B%5Cfrac%7B0.387%5Ccdot%20%2812.486%5Ctimes%2010%5E%7B6%7D%29%5E%7B%5Cfrac%7B1%7D%7B6%7D%20%7D%7D%7B%5Cleft%5B1%20%2B%20%5Cleft%28%5Cfrac%7B0.559%7D%7B0.733%7D%5Cright%29%5E%7B%5Cfrac%7B9%7D%7B16%7D%20%7D%5Cright%5D%5E%7B%5Cfrac%7B8%7D%7B27%7D%20%7D%7D%20%20%5Cright%5C%7D%5E%7B2%7D)

Answer:
the correct answer is C, E’= 4E
Explanation:
In this exercise you are asked to calculate the electric field at a given point
E = 
indicates that the field is E for r = 2m
E =
(1)
the field is requested for a distance r = 1 m
E ’= k \frac{q}{r'^2}
E ’= k q / 1
from equation 1
4E = k q
we substitute
E’= 4E
so the correct answer is C