a wagon rolling at a constant velocity of 4 m/s
Step-by-step explanation
acceleration is the rate of change in velocity over time,The change in the velocity of an object could be an increase or decrease in speed or a change in the direction of motion
so, let's check every option
Step 1
a)wagon rolling at a constant velocity of 4 m/s
as there is not change in the velocity the wagon is not accelerating s,so this describes zero acceleration
a) true
Step 2
b)a toy car coming to a stop as it rolls onto a rocky path
the toy car is changing its velocity , from some value to zero ( rest), so there is acceleration
Step 3
a cannonball being shot into the air
as the cannon starts from the rest , and the force from the powder shot it so, it changes is speed,so there is acceleration
Step 4
a rock falling from a cliff:
when a rock is falling is due to the acceleration of the gravity, so there is an acceleration
therefore, the answer is
a wagon rolling at a constant velocity of 4 m/s
I hope this helps you