For this case we have that by definition, the momentum equation is given by:

Where:
m: It is the mass
v: It is the velocity
According to the data we have:

Substituting:

On the other hand, if we clear the variable "mass" we have:

According to the data we have:

Thus, the mass is 
Answer:

By Bernoulli Theorem, We know, that for any two points in the pipe, total energy would be same.
Pressure Energy + K.E. of 1st pipe = Pressure Energy + K.E. of 2nd pipe
[ No need to consider Potential energy as height isn't mentioned]
P₁ + mv₁²/2 = P₂ + mv₂²/2
So, we know, P + mv²/2 = constant
As value of kinetic energy is larger in larger in 2 in. pipe [ 'cause area is indirectly proportional to velocity ], Value of pressure energy would be smaller in it. So, pressure energy will be higher in the pipe of 3 in.
In short, option A would be your correct answer.
Hope this helps!
Answer:
Explanation:
Given

Motor reverse its direction when \omega =0



(b)





Hello,
Here is your answer:
The proper answer to this question will be option A "An accelerating electric point charge (electron) emits electromagnetic waves." That's because electromagnetic waves are formed by motion of electrically charged particles (electrons)!
Your answer is A!
If you need anymore help feel free to ask me!
Hope this helps!