What is the reason behind the shifting of earth plates, which is responsible for earthquakes?
The earth deep below is very hot and even rocks and metals are in a liquid state. Due to convection this material rises and falls, the way liquid in a beaker heated over a gas stove would. The heat inside the earth comes from gravitational falling of heavier material as also from radio activity. These moving currents of matter carry the solid crust with them. Rotation of the earth is also implicated. This is believed to be the reason for movement of plates. Which forces are acting on a person ascending in an elevator? Why is the formula used to calculate this force described as total mass of lift (acceleration of lift + acceleration due to gravity);i.e. m(a+g) I am very pleased that you asked this question. It is true that the force acting on the floor of the lift will be m(g+a) mg is the force due to your weight even when the lift was stationary while (m a) is the force due to the fact that the lift is accelerating. In other words, the formula you have given is correct. (Incidentally
