Hello!

I'm sure we ignore air resistance. Then the height of an object at time t is given by the rule

`h(t) = h_0 - (g*t^2)/2,`

where `h_0` is the initial height and t=0 corresponds to the moment when object was dropped.

Object hits the ground means `h(t_1)=0.` This is...

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Hello!

I'm sure we ignore air resistance. Then the height of an object at time t is given by the rule

`h(t) = h_0 - (g*t^2)/2,`

where `h_0` is the initial height and t=0 corresponds to the moment when object was dropped.

Object hits the ground means `h(t_1)=0.` This is a simple equation:

`180 - (10*t_1^2)/2 = 0,`

`t_1^2 = 36,` `t_1` = **6(s)**.

(the solution `t_1=-6` isn't suitable, t must be >=0)