Atoms have no electric charge because they A. Have an equal number of charged and non charged particles.

B. Have neutrons in their nuclei.

C. Have an equal number of electrons and protons

D. Have an equal number of neutrons and protons

Answer choice c is the correct choice

Each time they race up a hill, they gain more potential energy (by rising higher in the air), but they compensate for it by losing some kinetic energy too (by slowing down). That's why rollercoaster cars always go slower in the higher bits of a ride and faster in the lower bits.