CLASSICAL MECHANICS & THERMODYNAMICS - Chapter 1, Exercise 1 Solution
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Calculating Final Velocity from Constant Acceleration

PROBLEM
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A car starts from rest (u = 0 m/s) and accelerates at a constant
4 m/s^2 for 6 seconds. Using v = u + at, calculate the car's final
velocity.

SOLUTION
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Using the real SUVAT equation:
    v = u + at

Substitute the given values:
    u = 0 m/s
    a = 4 m/s^2
    t = 6 s

    v = 0 + (4 x 6)
    v = 0 + 24
    v = 24 m/s

ANSWER: The car's final velocity is 24 m/s.

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WHY THIS WORKS AS AN ANSWER

This equation directly expresses the real definition of constant
acceleration: velocity increases by the same fixed amount (a) every
second. Starting from rest (u = 0), after t seconds the object has
gained a total of a x t in velocity, since acceleration has been
adding exactly a m/s of speed for every one of the t seconds elapsed.
With u = 0 in this specific case, the equation simplifies to v = at
directly - the final velocity is simply the acceleration multiplied by
how long it has been acting.