A truck speeds up from a velocity of 6m/s to 14 m/s in 4 seconds. What is the trucks acceleration?

As it is given here

initial speed is

v_i = 6 m/s

After 4 seconds the final speed is

v_f = 14 m/s

so here we can use the formula of acceleration using kinematics

a = / frac{v_f - v_i}{t}

a = / frac{14 - 6}{4}

a = 2 m/s^2

so here it will accelerate at 2 m/s^2 rate.