At A Point
- 1. At a PointBy: Cali Oehman, Preslie Lilly, and Andrew Parrish
- 2. NotesThe Formula for solving At a Point problems is: s(t)=-16t2+vot+so
- 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.
- 7. NotesWe want to know the value of t when it will be s(t)=height. To find out we substitute the height for s(t), and solve the quadratic equation for t.*Always be sure that your height equals 0.EXAMPLE: 20= -16t2+85t+120 subtract 20 from each side of the equation. 0= -16t2+85t+100Then just solve for (t) using the quadratic formula!
- 8. Your two answers will be the time that it hits the given height.Example #1A ball is tossed from 4 feet above ground. It is released with an upward velocity of 50 feet per second. When will be ball be 40 feet above the ground? A. Approximately 2.07 seconds B. Approximately 1.05 seconds C. Approximately 3.85 seconds D. Approximately 3.71 seconds
- 9. Example #2A 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