Answer:
The new energy density is same as initial energy density u0 as it is independent of plate dimensions
Explanation:
As we know that energy density is total energy per unit volume
so we know that isolated plates of capacitor is placed here

here we have energy density given as

so we have

so it is independent of the dimensions of the plate while total charge on the plates is constant always
so energy density will not change and remains the same
Force equals mass time acceleration. Weight is a force and it can replace force in the equation. The acceleration would be gravity, which is an acceleration.
1.)
Fw (weight) = m (mass) · g (gravity, 9.8 m/s²)
Fw = m * 9.81 m/s²
560N = m · 9.81 m/s²
m ≈ 57.08 kg
2.)
d = 350 meters
t = 65 seconds
velocity = d/t
velocity = 350 meters / 65 seconds
velocity ≈ 5.38 meters/sec
3.)
Force = 35N
Distance = 2 meters
Work = Force · Distance
Work = 35N · 2 meters
Work = 70 J