Vertical Projectile Motion
Free fall, equations of motion in vertical plane
Vertical Projectile Motion
Vertical projectile motion is motion under gravity alone (ignoring air resistance). Acceleration is always g = 9.8 m/s squared downward. At maximum height, velocity is zero. Equations of motion apply with a = plus or minus g.
Example
Worked Example
Ball thrown upward at 20 m/s (up positive, a = -9.8 m/s squared). Time to max height: 0 = 20 + (-9.8)t, t = 2.04 s. Max height: s = 20(2.04) + 0.5(-9.8)(2.04 squared) = 20.4 m. Total time = 4.08 s.
Note
Exam Tip
Draw position-time, velocity-time, and acceleration-time graphs. On a v-t graph, the line has constant negative slope (-9.8). The area under the v-t graph gives displacement.
Key Vocabulary
ProjectileAn object moving under the influence of gravity alone
Free fallMotion where gravity is the only force acting on an object
Gravitational accelerationAcceleration due to gravity, approximately 9.8 m/s squared near Earth
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