Ceres has an orbital semi-major axis = 2.768 au. what is ceres’ orbital period?

4.6 years

Explanation:

According to Kepler’s Third Law of Planetary motion “The square of the orbital period  of a planet is proportional to the cube of the semi-major axis (size) of its orbit”:

(1)  

However, if is measured in Earth years, and is measured in astronomical units (unit equivalent to the distance between the Sun and the Earth), equation (1) becomes:  

(2)  

Knowing and isolating from (2):  

(3)  

(4)  

Finally:  

This is Ceres' orbital period

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.

energy stored in the capacitor= 9.72 x 10⁻⁴ j

explanation:

the energy stored in the capacitor is given by

e= 1/2 c v²

e= energy stored

c= capacitance= 1.5 µc= 1.5 x 10⁻⁶f

v= potential difference=36 v

so energy stored= e= 1/2 (1.5 x 10⁻⁶) (36)²

energy stored= 9.72 x 10⁻⁴j