5.3. Key Concepts http://www.ck12.org
5.3 Key Concepts
- In projectile motion, the horizontal displacement of an object from its starting point is called itsrange.
- Vertical (y) speed is zero only at the highest point of a thrown object’s flight.
- To work these problems, separate the “Big Three” equations into two sets: one for the vertical direction, and
one for the horizontal. Keep them separate. - The only variable that can go into both sets of equations is time. You use time to communicate between the
two directions. - Since in the absence of air resistance there is no acceleration in the horizontal direction, this component of
velocity does not change over time. This is a counter-intuitive notion for many. (Air resistance will cause
velocity to decrease slightly or significantly depending on the object. But this factor is ignored for the time
being.) - Motion in the vertical direction must include the acceleration due to gravity, and therefore the velocity in the
vertical direction changes over time. - The shape of the path of an object undergoing projectile motion in two dimensions is a parabola.