If an object is thrown straight up with an initial velocity of 8m/s and takes 3 seconds to strike the ground, from what height was the object thrown?

s = it+1/2 at²

s= 8×3+1/2 (10)(3)²

s = 24+45

s= 69

the object was thrown from a height of 69 meters

69m

Explanation:

initial velocity (v)= 8m/s

a= 10m/s

t=3s

Δx=?

Δx=v(t)+1/2at^2

Δx=8(3)+1/2(10)(3)^2

=24+(5)(9)

=24+45

Δx=69m

v=ir = 3x15 =45 v