FYKOS Year 27 Series 2 Problem 2 — Flying wood · FYKOS 27 #27.2.2

Physics · mechanics · electromagnetism

Problem

We have a wooden sphere at a height of

h=1\;\mathrm{m}

above the surface of the Earth which has a perimeter of

R_{Z}=6378\;\mathrm{km}

and a weight of

M_{Z}=5.97\cdot 10^{24}\;\mathrm{kg}

. The sphere has a perimeter of

r=1\;\mathrm{cm}

and is made of a wood which has the density of

ρ=550\;\mathrm{kg}\cdot \mathrm{m}^{−3}

. Assume that the Earth has an electric charge of

Q=5C

. What is the charge

q

that the sphere has to have float above the surface of the Earth? How does this result depend on the height

h?