A car was parked on the side of a hillside road at the top of a hill. Unbeknown to the owner, its parking brake failed and a tremor from nearby construction set it in motion with negligible initial speed down the hill. Assume the acceleration was constant down the hill, the car was given a speed ticket by a traffic camera at the foot of the hill, which measured the speed of the car at 21.0 m/s. The video recording showed the car took 31.0 seconds to slide down the hill. How long is the road on the side of the hill?