Answer:
30 N
Explanation:
Since the car travels at a steady speed of 20m/s and has a driving force of 30N, there is no net acceleration and thus, the resistive force is also 30 N in magnitude but in the opposite direction to the driving force. This is shown below.
F - f = f' where F = driving force = 30 N. f = resistive force and f'= net force.
f' = 0 since there is no acceleration. So,
F - f = 0
F = f = 30 N
