A = 4\pi r^2
A = 4\pi (2\mu m /2)^2 (10^{-6}m/1\mu m)^2 (1mm/10{-3})^2
A = 1.33*!0^{-5}MM^2
Here it is an application of Newton's III law
as we know by Newton's III law that every action has equal and opposite reaction
So here as we know that two boys jumps off the boat with different forces
from front side of the boat the boy jumps off with force 45 N which means as per Newton's III law if boy has a force of 45 N in forward direction then he must apply a reaction force on the boat in reverse direction of same magnitude
So boat must have an opposite force on front end with magnitude 45 N
Now similar way we can say
from back side of the boat the boy jumps off with force 60 N which means as per Newton's III law if boy has a force of 60 N in backward direction then he must apply a reaction force on the boat in reverse direction of same magnitude
So boat must have an opposite force on front end with magnitude 60 N
So here net force due to both jump on the boat is given by



so boat will have net force F = 15 N in forward direction due to both jumps
The correct answer of this question is : A) Change alternating current into direct current.
EXPLANATION :
As per the question, we are given vacuum tube. Vacuum tube can be of various types. Normally it contains two electrodes called cathode and anode which are enclosed in an evacuated glass chamber . There are also other types of vacuum tubes which contain extra electrodes like control grid .
The vacuum tube can be used as a rectifier. It means that it can be used as an electronic device which will convert alternating current into direct current. It may be a half wave rectifier or a full wave rectifier. Actually the direct current obtained during the rectification of alternating current is pulsating in nature.
Hence, the correct answer is that a vacuum tube can be used to change alternating current into direct current.
Explanation:
Fe₂O₃ + CO → Fe₃O₄ + CO₂
Balancing the equation above, we can derive simple mathematical equations that are very easy to solve.
aFe₂O₃ + bCO → cFe₃O₄ + dCO₂
a,b,c and d are the coefficients needed to balance the equation above;
Conserving Fe; 2a = 3c
O: 3a + b = 4c + 2d
C: b = d
let a = 1;
c = 
Since b = d
3a + d = 4c + 2d
3a = 4c + 2d - d
3a = 4c + d
a = 1, c = 
3 = 4 x
+ d
d = 
b = 
multiplying a, b, c and d by 3:
a = 3 b = 1 c = 2 and d = 1
3Fe₂O₃ + CO → 2Fe₃O₄ + CO₂
Learn more:
Balanced equation brainly.com/question/2612756
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Answer:
Acceleration of the second particle at that moment is given as

Explanation:
As we know that both cars are connected by same spring
So on this system of two cars there is no external force
So we will have

now we have



now we have

so we have
