260 joules is hopefully right.
The effective spring constant of the system is 39.6 N/m
Explanation:
The frequency of oscillation of a spring-mass system is given by

where
k is the spring constant of the system
m is the mass
In this problem, we have:
f = 29 Hz is the frequency of vibration of the eyeball system
m = 7.5 g = 0.0075 kg is the mass
We can therefore re-arrange the equation to find the effective spring constant of the system. We find:

#LearnwithBrainly
To change from mass to weight is Fw = 30 kg * 9.8 m/s^2 = 294 N. To change from weight to mass divide by gravity (9.8 m/s^2).
It depends on the angle of the earth, and our point of view. A full moon would occur if we were to be right in front of it.