Which is the heaviest of the natural elements? A. potassium

B. sodium

C. uranium

D. iron

The graph below represents the work done by a student while running up flights of stairs. determine the student's power output after 10 seconds: 1600 j/s 8000 j/s 160 j/s 800 j/s

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.

Gasoline comes from petroleum, which is made from ancient living things. petroleum, therefore, contains a type of energy. a. heat b. nuclear c. biological d. chemical potential