A radioactive material A (decay constant λA) decays into a material B (decay constant λB) and then into a material C (decay constant λC) which is also radioactive. Determine the amount of material C remaining after a time t

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.