Velocity
The rate of change of displacement with time, calculated as v = Δs/Δt (where s is displacement and t is time). A vector quantity (has direction), measured in m/s. Instantaneous velocity is the velocity at a specific instant; average velocity is total displacement divided by total time.
Formula
v = Δs / Δt
Real World
A Tesla Model S accelerating from 0 to 27 m/s (≈60 mph) due east has a velocity of 27 m/s east — whereas a car doing the same speed in a roundabout has changing velocity even though its speed is constant.
Exam Focus
On displacement–time graphs, draw a tangent at the point to find instantaneous velocity; do not just read off the y-axis.
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