Question

A biker rides on a straight line such that his displacement from the starting point is given as x = 2t + t2. what is the average velocity (average rate of change of displacement) for between t = 4s and t = 6s?

Answer 1

we are given with the formula on the distance the biker rides on a straight line represented by the equation x = 2t + t2. to find the velocity, we take the first derivative of the equation, that is 

x' = 2 + 2t 
at t = 4
x'= 2+ 8 = 10 m/s
at t = 6
x' =2 + 12 = 14 m/s

average velocity: 12 m/s