What is the main natural force responsible for mass movement of rocks and debris?

Aprisoner is forced to go into one of three rooms, but he can choose which room. the first room is ablaze with fire. the second one is rigged with explosives that will go off as soon as he enters. the third contains a pair of lions who haven't eaten in years. which room should he choose to survive?

Why does gravity have a lesser than grater effect on higher altitudes?

If a person whirls an object horizontally in a counter clockwise direction and the string breaks at point p as shown, what path will the rock follow?