Explain how a bucket of water would be an open system?

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative

Which of the following are guidelines to follow for obtaining accurate observations

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.