Answer:So far scientists have not found a way to determine the exact age of the Earth directly from Earth rocks because Earth's oldest rocks have been recycled and destroyed by the process of plate tectonics. If there are any of Earth's primordial rocks left in their original state, they have not yet been found.
Through Air sounds travels approximately 343 meters/second. Why the difference? Because the closer together the molecules in a substance are, the faster sound will travel through that medium.
the machine shown in figure 9.9 is called a wheele and axle. It's a form of lever. the effort arm can rotate in a complete circle, which is the center of the axle.
