If two simple machines are compounds, the velocity ratio of the system is equal to​

Which is not true about oxygen-17 and oxygen-18?

Apebble is thrown into a calm lake, ripples are formed from the center and move outward. the water particles in the lake travel in a circular pattern that moves up and down on the surface of a lake, and the energy travels a) diagonally. b) downward. c) horizontally. d) upward.

In a good thermo flask the main cause of heat loss is