A car travelling at 28 m/s brakes until it stops completely after travelling a distance of 15 m. Calculate the deceleration of the car.

·        Firstly, we need to note down what we have: distance travelled, s =15 m; initial velocity, u = 28 ms^-1; final velocity, v = 0 because the car comes to rest; we are looking for the deceleration hence a; since we are using s, u, v and a, we need to use the "suvat" equation that contains those four letters ----- v² = u² + 2as·        By rearranging the equation ---- a = (v² - u²) / 2s = -28² / (2 x 15) = -784/30 = -26 ms^-2 (the minus sign is because deceleration is a decrease in speed rather than an increase)