You see a quarter at the bottom of a fountain. how does refraction of light waves affect the position when you reach down to get it?

Iwill give 30 points to whoever answers ! what is the formula for actual mechanical advantage and ideal mechanical advantage?

Which lists the fundamental forces in order, from strongest to weakest? strong nuclear, weak nuclear, electromagnetic, gravitational strong nuclear, electromagnetic, weak nuclear, gravitational gravitational, weak nuclear, electromagnetic, strong nuclear electromagnetic, gravitational, strong nuclear, weak nuclear

The electric potential a distance r from a small charge is proportional to what power of the distance from the charge? a. r^-1 b. r c. r^-2 d. r^2