A thermos bottle works well because: a. its glass walls are thin
b. silvering reduces convection
c. vacuum reduces heat radiation
d. silver coating is a poor heat conductor
e. none of the above

The most important difference between a wedge and an inclined plane is a. their size b. their shape c. how they are used d. what they are made of

Which statement correctly describes a step-up transformer? a. it increases the amount of electric energy available. b. it increases the voltage of an electric current. c. it changes direct current into alternating current. d. it has more loops of wire in its primary coil.

Drag each item into the proper state of matter category.