Answer:
(A) 421 J energy stored in the capacitor for one flash.
(B) The value of capacitance is 0.0537 F
Explanation:
Given :
(A)
Time 
Average power
W
From power equation,

So energy in one light is given by,

J
Since efficiency is 95 % so we can write, energy stored in one flash,
J
(B)
From the formula of energy stored in capacitor,

Where
and
V



Answer:
Restoring force of the spring is 50 N.
Explanation:
Given that,
Spring constant of the spring, k = 100 N/m
Stretching in the spring, x = 0.5 m
We need to find the restoring force of the spring. It can be calculated using Hooke's law as "the force on a spring varies directly with the distance that it is stretched".


F = 50 N
So, the restoring force of the spring is 50 N. Hence, this is the required solution.
I believe the answer is D