Answer:
V = 40 m/s^2
Step-by-step explanation:
horizontal force ,

mass, m = 6kg
time, t = 10s
frictional force,

net force

40N - 16N = 6 x a (1)
in this case you apply the equation of motion
the block is at rest, initial velocity is, U = 0
final velocity is is what we are looking for, V

since U is 0 we have
a = V/t (2)
subsituting (2) into (1)


cross multiply
240 = 6 x V
divide both sides by 6
V = 40 m/s^2