<em>An object is dropped from a bridge and allowed to freefall to the ground. The height of the object over time can be modeled using h(t)=144-16t2. How many seconds will it take the object to reach the ground? 2 seconds 3 seconds 9 seconds 16 seconds</em>
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Given the height of an object modelled by the expression;
<em>h(t)=144-16t²</em>
The object will reach the ground when h(t) = 0
Substitute into the formula
0 = 144 - 16t²
-144 = -16t²
144 = 16t²
Swap
16t² = 144
t² = 144/16
t² = 9
Square root both sides
√t² = ±√9
t = ±3secs
<em>Since the time cannot be negative, hence the object will reach the ground 3 seconds after</em>
