In below two similar questions Why one velocity is negative, and the another is not?

Suppose a hiker, standing near the edge of a 433 meter tall cliff, throws a rock downward vertically off the cliff at a speed of 64 meters per second. Determine the velocity and acceleration of the rock at the moment the rock impacts the ground. Round solutions to the nearest thousandth, if necessary. The rocks's speed at the point of impact is 112.17 ~/ 0\" meters per second v V o\" The rocks's acceleration at the point of impact is 0\" meters per second squared v Suppose a hiker, standing near the edge of a 289 meter tall cliff, throws a rock downward vertically off the cliff at a speed of 56 meters per second. Determine the velocity and acceleration of the rock at the moment the rock impacts the ground. Round solutions to the nearest thousandth, if necessary. The rocks's velocity at the point of impact is 793.81 \\/ 0\" meters per second v V o\" The rocks's acceleration at the point of impact is 0" meters per second squared v