Answer:
Time = 6 years
Explanation:
First, we will calculate the no. of half life periods required to reduce the mass of Protactinium to the given value:

where,
n = no. of half-life periods = ?
m = initial mass = 86.3 g
m' = remaining mass = 10.8 g
Therefore,

Since the bases are the same. Therefore equating powers:
n = 3
Now we calculate the time:

<u>Time = 6 years</u>
Because the same sides(N and N, or S and S) are facing each other in magnet 4 and 5. Also in magnet 2 and 3.
Answer:
centripetal force is a net force that acts on an object to keep it moving along a circular path and elastic force acts to return a spring to its natural length