Question

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?

Answer 1

Answer:

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

Answer 2

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