The time elapsed since you stopped the stopwatch is 0.41 s.
<em>Your question is not complete, it seems to be missing the following information;</em>
"The velocity of the ant is 2 m/s"
The given parameters;
- velocity of the ant, v = 2 m/s
- change in position of the ant, Δx = 0.81 m
- initial time, t₁ = 4 s
- time when the ant was noticed, = t₂
Velocity is defined as the change in displacement per change in time of motion of an object.
The time elapsed since you stopped the stopwatch is calculated as;
Thus, the time elapsed since you stopped the stopwatch is 0.41 s.
Learn more here: brainly.com/question/18153640