An object releases from rest at a height of 0.5km. how long does it take to reach the ground

Answer: t = 10s

Explanation:

Assuming there's no air resistance,

Initial velocity (u) = 0 m/s

Acceleration by gravity (a) = 9.81 m/s^2

Displacement (s) = 500m

Time taken (t) = ?

Now,

Use formula,

s = u*t + (1/2) * a*t^2

s = 0*t + (1/2) * 9.81*t^2

500 = 4.905*t^2

t = 10s