Answer:
Estimation: year 1110.
Explanation:
We need to know how much time it takes to move 100 arcseconds if it moves at 0.11 arcsecond per year. Similarly to any velocity equation
, where in our case the distances are angular, we will obtain the time by doing:

Which, considering from 2019, the explosion ought to have been observed around 1110 (in reality it was observed by Chinese astronomers in 1054).
Answer:
(i) Electric field outside the shell:
For point r>R; draw a spherical gaussian surface of radius r.
Using gauss law, ∮E.ds=q0qend
Since E is perpendicular to gaussian surface, angle betwee E is 0.
Also E being constant, can be taken out of integral.
So, E(4πr2)=q0q
So, E=4πε01r2q
Answer:
Explanation:
Given mg = 4N .
m = 4 / g
At the bottom of the swing let centripetal acceleration be a
T - mg = ma
9 - 4 = ma
5 = 4 a / g
a = 5g / 4