A mover pushes a box with 400N a distance of 3m in 55s.

Answer(b) both involve the use of levers;

Idon't understand is there supposed to be a list or something if there is pm or add in under this message i will do my best to .

Because there is no air in the jar, the vibrations can not travel through the air and create sound.  (that's why there is no sound in space, there is no air)

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.