# He doesn't have a lead foot, it just looks that way

Since the speed of light is finite (equal to $$c=3 \times 10^8 (m/s)$$), when we observe an object that is moving with constant speed, it can actually appear to have an acceleration. We'll call this an "apparent acceleration". As an example, consider a car moving on a straight road with a constant velocity $$v=50~m/s$$. An observer stands a distance $$d=5~m$$ from the side of the road and watches the car. Find the maximum "apparent acceleration" in $$\mu m/s^2$$ the observer sees as she watches the car approach her and then move away.

Hint: Can you figure out the position the observer believes the car is at at each instant in time?

Details and assumptions

• 1 $$(\mu m)=10^{-6} (m)$$
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