In a nuclear power plant, the nuclear reaction is kept from going critical by keeping the rate of reaction safe. how do the control rods figure into this?

a. the controls rods absorb the excess heat produced in the reaction.
b. the controls rods absorb excess neutrons, keeping them from causing too many uranium atoms to split too quickly.
c. the control rods provide additional neutrons to keep the reaction going.
d. the control rods absorb excess uranium atoms so that the reaction doesn't happen too quickly.

Correct answer is B

Explanation:

Control rods in Nuclear reactor:

During nuclear reaction when a heavy nucleus break up into two light nuclei that time neutron are release and these neutrons further break up other nucleus which release more neutrons which lead to a chain reaction. the nuclear reaction is kept from going critical by keeping the rate of reaction safe by using control rods. Controls rods absorb excess neutrons, keeping them from causing too many uranium atoms to split too quickly.

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.

3. dark matter

empty space could also be a simple vacuum