A crab scuttles from x₀ = -6 m to x = -1 m. Enter the displacement Δx in meters, including the sign.
Here is the car from the first kinematic equation, one more time. It pulled away from the light at 3 m/s, accelerated at 2 m/s² for 5 s, and reached 13 m/s.
Now a different question: how far did it travel in those 5 s? v = v₀ + at can't answer that — there is no distance anywhere in it.
The car covered some stretch of road in those 5 s. That stretch, the displacement Δx, is the unknown.
First, write down the values from the question, and mark the one you want.
We want Δx, so we need an equation that contains it. This is the second kinematic equation.
An object with starting velocity v₀ accelerates at a constant rate a for a time t. Which equation gives its displacement?
The final velocity never appears in it. Reach for this equation when the question gives a time and asks for a distance.
A motorboat passes a buoy at 8 m/s and speeds up steadily at 3 m/s² for 2 s, ending 22 m past the buoy. In Δx = v₀t + ½at², which of the boat's numbers plays the part of Δx?
Your turn
A problem gives an object's starting velocity, its constant acceleration, and the time it moves. Which pairing about Δx = v₀t + ½at² is correct?
In Δx = v₀t + ½at², what does the term v₀t tell you?
Using Δx = v₀t + ½at², a student finds Δx = -30 m for a cart's 5 s run. What does the minus sign say?