It's empty or fairly large, making the sounds from your hands bounce of the walls and therefore having it echo
I think you might've forgotten something. There is no labels, pictures, or any options. Add some more stuff and I'd be able to help out.
by experimenting the layers of the earth
C)1125 J because the formula for kinetic energy is 1/2 multiplied by mass multiplied by volume to the second power. So 1/2 multiplied by 10 multiplied by 15 to the second power is 1125 if that makes since.