Vertical motion?

Question

a ball is thrown vertically upward from a height of 6m. if it misses the thrower's hand and hits the ground 6s after it was thrown, what is the initial velocity?

Answer 1

f

Answer 2

v=u+at

0=u+10*6

0=u+60

0-u=60

u=60-0

u=60m/s or 6.0m/s

Answer 3

using the equations of motions :

Y=Yo+V*t-0.5*g*t^2

0=6+6*V-0.5*10*6^2

THEN, solving for V=29m/sec

Answer 4

Vector Problem: Take up as positive.

Displacement is 6m down, s = -6m

Acceleration due to gravity = 9.81m/s² down, a= -9.81

Initial velocity = um/s up So u is positive

time = 6 sec scalar no sign.

s = ut + 1/2 at²

-6 = u*6 + 1/2 (-9.81) 6²

-6 = 6u - 176.58

-6u = -176.58 - 6

6u = 176.58+6

6u = 176.58

u = 176.58/6

u = 29.43m/s