Sketch the velocity-time graphs for the following motions.
a. a city bus that is moving with a constant velocity
b. a wheelbarrow that is speeding up at a uniform rate of acceleration while moving in the positive direction
c. a tiger that is speeding up at a uniform rate of acceleration while moving in the negative direction
d. an iguana that is slowing down at a uniform rate of acceleration while moving in the positive direction
e. a camel that is slowing down at a uniform rate of acceleration while moving in the negative direction