Which of the following would you describe as a change in state?
a) melting ice
b) burning paper
c) film being exposed to light
d) a piece of paper being cut in half

Which of the following situations is impossible? a) an object has velocity directed east and acceleration directed east. b) an object has zero velocity but non-zero acceleration. c) an object has constant non-zero velocity and changing acceleration. d) an object has velocity directed east and acceleration directed west. e) an object has constant non-zero acceleration and changing velocity.