Kinematic: An object drop 20m from a cliff. If it started at rest and is going 20m/s just before it hits the ground, what is it's acceleration?

h=average v * time average v = (0 + 20) / 2 = 10 so: h = 20 = 10 * t - -> t = 2 sec final v = v0 + at v0=0 - -> 20 = 0 + a*2 - > a = 10 m/s2

10 m/s²

Explanation:

a = ?

h = 20m,

u (initial velocity) = 0 m/s (since it starts at rest,

v = 20m/s

Using equation of motion,

V² = U² + 2as

V² - U² = 2as

a = (v² - u²) / 2s

a = (20² - 0) / 2 * 20

a = 400 / 40

a = 10 m/s²