The average acceleration of an object can be calculated using the equation: acceleration = change in velocity / time taken, a = ∆v/t. acceleration, a, in metres per second squared, m/s²; change in velocity, ∆v, in metres per second, m/s; time, t, in seconds, s. • An object that slows down is decelerating. • Students should be able to estimate the magnitude of everyday accelerations. • The acceleration of an object can be calculated from the gradient of a velocity–time graph. • Students should be able to: draw velocity–time graphs from measurements and interpret lines and slopes to determine acceleration.