Answer:
Position at t= 4 seconds is 144 m
Explanation:
It is given that acceleration, a = 18 t, where t is the time.
We know that Velocity, 
Substituting value of a,
Velocity, 
We know that at t = 0, v = -12 m/s
So, 
So velocity, 
We also know that displacement, 
Substituting value of v,
Displacement, 
We know that at t = 0, particle is at origin, x =0.
So, 
Displacement, 
At t = 4 seconds

Position at t= 4 seconds is 144 m
The material that the snails are moving on affects their speed. On a smooth material, (petri dish) the snails moved the fastest. On a rough material (sandpaper) the snails moved the slowest. On dirt, a compromise between smooth and rough, the snails moved at a medium pace. The material and possibly friction affect this.