Which type of energy do you always have at the top of the first hill on a roller coaster?

It was crowded with sewer like smells. bad sewer systems

The density of the block of iron is lees than the density of mercury but the density of the block of iron is greater than the density of water

You need to calculate the string in between two masses

Answer;

hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.

explanation; convection currents are the circular pathways taken by a fluid that enhances heat transfer by the process known as convection which occurs in fluids.convection currents transfer heat from one place to another by mass motion of a fluid. earth mantle is in a semi-liquid state and behaves like any other fluid, rising up from the bottom of the mantle after becoming hotter and less dense from heat of the earth's core, as the rock loses heat into the earth's crust it becomes cooler and more dense, then sinking back down to the core, then repeating the cycle.