Question

an object is dropped from a platform 100 feet high. ignoring wind resistance, what will its speed be when it reaches the ground?
____ ft/s
○ 6400
○ 2 000
○ 80
○ 44

Explanation:

Step1: Recall the free - fall formula for velocity

The formula for the velocity of an object in free - fall (ignoring air resistance) is \(v=\sqrt{2gh}\), where \(g\) is the acceleration due to gravity and \(h\) is the height from which the object is dropped. In the English system, the value of \(g\) is approximately \(32\space ft/s^{2}\) and \(h = 100\space ft\).

Step2: Substitute the values into the formula

Substitute \(g = 32\space ft/s^{2}\) and \(h=100\space ft\) into the formula \(v=\sqrt{2gh}\).
First, calculate \(2gh\): \(2\times32\times100=6400\).
Then, take the square root of \(6400\): \(v = \sqrt{6400}=80\space ft/s\).

Answer:

80