First Equation of Motion formula:
story, analogy and memory trick
The First Equation of Motion formula is v = u + at. The final velocity equals the initial velocity plus the acceleration multiplied by the time, for straight-line motion with constant acceleration.
The First Equation of Motion formula
- vfinal velocity, in m/s
- uinitial velocity, in m/s
- aconstant acceleration, in m/s²
- ttime taken, in seconds
The story
A bus leaves a stop already moving at speed u. Every second the driver presses the accelerator and adds a little more speed, which is the acceleration a. After t seconds the speedometer shows v: the speed it started with plus everything it gained.
Real-life analogy
Think of a bank balance. u is the opening balance, a is the amount you save each month, t is the number of months, and v is the balance you have now.
Memory trick
Read it as 'Final = Start + Gain', where the gain is a × t.
Exam tip
Use it only for constant acceleration. Give a a negative sign when the object slows down, and keep the units consistent: m/s, m/s² and s.
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More Physics formulas
Ohm's Law
V = I × R
The current through a conductor is directly proportional to the voltage across it, as long as its resistance and temperature stay constant.
Read the storyNewton's Second Law
F = m × a
The net force on an object equals its mass multiplied by its acceleration, so the same push speeds up a lighter object more than a heavier one.
Read the storyKinetic Energy
KE = ½ × m × v²
The kinetic energy of a moving object is half its mass times the square of its speed, so speed matters far more than mass.
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