As this is a straight-line motion problem, the following formulas will be used to solve for acceleration, which is used to solve for displacement:
Vf = Vi + a * t
s = Vi * t + 1/2 (a*t^2)
Where: Vf = final velocity
Vi = initial velocity
a = acceleration
t = time
s = displacement
Using eq.1 :
35 m/s = 0 m/s + a * 20 s
a = 35 / 20
a = 1.75 m/s^2
Using eq.2:
s = 0 * 20 + 1/2 (1.75 * 20^2)
s = 350 m
Therefore, the correct answer is C.
