After how many seconds does the motorcycle have positive acceleration? 1 2 3 4

What is the momentum of a 2 kg object moving at 15 meters per second

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.

What does si stand for,when referring to a system of measurement