The slope of a speed-time linear graph is acceleration direction speed velocity

The answer is acceleration because the slope is how the sharp or steep the speed is increased. In a velocity versus time graph, any small part of the curve can be written as V = m T + b; where the slope of the curve is equals to dV/dT. b = U is the primary speed when time is equals to 0. In physics, the change in velocity over an interval of time is defined as acceleration.