The equation v22 = vo2 + 2aΔy is used to determine the change in position, acceleration, or velocity of a particle under the influence of a quadratic force. on earth, the acceleration value in this equation would, under normal circumstances, be a= -9.8 m/s2. so, this substitutes into v22 = vo2 + -19.6Δy In this Δy = v22 - vo2 / -19.6 Lets now assume that v22 is 0, the crest of a projectiles motion. Δy = 0 - vo2 / -19.6 If the objects initial v is facing upwards, then obviously the net Δy would be positive. Now, keeping all conditions the same, lets assume that the acceleration is 9.8m/ss upwards This would yield Δy = 0 - vo2 / 19.6 Δy would thus be negative, and the object would be thrown downwards, accelerating upwards.