Projectile Motion Example

Let's say you're on top of a cliff, which drops vertically 150 m to the ocean below. You throw a ball with an initial speed of 8.40 m/s at an angle of 20 degrees above the horizontal.

(a) How long does it take before it hits the water?

(b) How far is it from the base of the cliff to the point of impact?

As usual, be as systematic as possible. Draw a diagram, choose a coordinate system, and organize your data.

Origin: the base of the cliff

Positive directions: +x right and +y up

X Info. Y Info.
Initial positionxo = 0 yo = +150 m
Final position x = ? y = 0
Initial velocity vox= +vo cos(q)
= +7.893 m/s
voy= +vo sin(q)
  = +2.873 m/s
Acceleration ax = 0 ay = -9.8 m/s2