Question

An elephant, mass 1100 kg, stands on the ground above a point charge with +3 C of charge that has been buried 0.8 m beneath the ground. How much charge would you need to put on the elephant in order to make it float?

Answer 1

`2.56071* 10^(-7)\ C`

Step-by-step explanation:

k = Coulomb constant =
`8.99* 10^(9)\ Nm^2/C^2`

g = Acceleration due to gravity = 9.81 m/s²

r = Distance between charge = 0.8 m

m = Mass of elephant = 1100 kg

`q_1` = Mass on first charge = 3 C

The electrostatic force will balance the weight of the elephant as the energy in the system is conserved

`(kq_1q_2)/(r^2)=mg\\\Rightarrow q_2=(mgr^2)/(kq_1)\\\Rightarrow q_2=(1100* 9.81* 0.8^2)/(8.99* 10^9* 3)\\\Rightarrow q_2=2.56071* 10^(-7)\ C`

The charge on the other particle is
`2.56071* 10^(-7)\ C`