Define relative density.​

What is the fate of the electrons that interact with a specimen in an electron microscope?

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

Will give brainliest! jay rides his 2.0-kg skateboard. he is moving at speed 5.8 m/s when he pushes off the board and continues to move forward in the air at 5.4 m/s. the board now goes forward at 13 m/s.a. determine jay’s mass.b. determine the change in the internal energy of the system during this process.(express your answer to two significant figures and include the appropriate units.)