Which of the following is the best definition of a physical change? A. A change in a substance where a new substance is formed
B. A change in a substance in which bonds are broken
C. A change in a substance with no new substances being formed
D. A change in a substance in which mass is conserved

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.