The document provides instructions for solving "at a point" physics problems involving projectiles moving vertically under the influence of gravity. It gives the formula s(t)=-16t^2+vot+so for calculating the height s of a projectile at time t, where vo is initial velocity and so is starting height. It explains that you set s(t) equal to the given height and solve the resulting quadratic equation to find the time(s) when the projectile reaches that height. Two examples of such problems are included.

1. At a Point By: Cali Oehman, Preslie Lilly, and Andrew Parrish

3. s(t) means the height at any time.

4. vo means the initial velocity.

5. so means the starting height when the projectile* is released.

6. t means time in seconds after the projectile* is released.*The projectile is the object you’re throwing.

9. Example #2 A bullet is fired vertically into the air from the ground at an initial velocity of 240 feet per second. When will the bullet return to ground level? A. -15 seconds B. 0 seconds. C. 15 seconds D. 3.87 seconds