Assuming 's' is the displacement, it's first derivative, i. I saw this physics joke somewhere and didn't understand it. #SushantSingRajput's this T-shirt had more IQ than whole of the Star Kids. It means don't be a jerk. ds/dt=Velocity , S=displacement and t=time d^2s/d^2t implies acceleration and d^ 3s/d^3t signifies the term Jerk. Your speed increases by 4 m/s over 2 seconds, so d2s dt2 = 42 = 2 m/s2.