If a vehicle is moving with a velocity of 20 m/s and it stops after 4 seconds, its final velocity will be 0 m/s.
The term "stops" implies that the vehicle comes to a complete halt, which means its final velocity is zero. When an object's velocity changes from a non-zero value to zero, it means the object has decelerated or undergone negative acceleration.
In this case, the vehicle's initial velocity is 20 m/s, and it stops after 4 seconds. Therefore, the change in velocity (Δv) is equal to the initial velocity (u) minus the final velocity (v), which is given by:
Δv = u - v
Since the final velocity is zero (v = 0), we can rearrange the equation to solve for the initial velocity:
Δv = u - 0 Δv = u
Therefore, the change in velocity (Δv) is equal to the initial velocity (u), which in this case is 20 m/s. This means that the vehicle's velocity decreased by 20 m/s over the 4-second interval.
So, the final velocity of the vehicle is 0 m/s.