**Free Fall Exercises**

**Exercise Four, Calculations For a Free Fall
Distance Traveled During a Given Time.-** A falling body travels 68 m in
the last second of its free motion: Assuming that the body started from rest,
determine how long it took to reach the ground and the altitude from which
the body fells.

A convenient axis is one with origin at the point of dropping and pointing downward.

Let t_{1} be the time one second before
hitting the ground and h1 the corresponding distance traveled.

Let t_{2} be the time to hit the ground
and h_{2} the corresponding distance traveled.

Then t_{2} - t_{1} = 1 s and
h_{2} - h_{1} = 68 m.

h_{1}=½ ·(9.8m/s^{2})t_{1}^{2}=4.9m/s^{2}t_{1}
and h_{2}=½ ·(9.8m/s^{2})t_{2}^{2}=4.9m/s^{2}t_{2}.

4.9m/s^{2}t_{2}^{2}-4.9m/s^{2}t_{1}^{2}=68
m, and replacing t_{1} by (t_{2}-1s) we get

4.9m/s^{2}t_{2}^{2}-4.9m/s^{2}(t_{2}
-1s)^{2}=68 m or 9.8t_{2}-4.9=68 , with t_{2} in seconds
giving t_{2} = 7.4 s.

The altitude is then h_{2} = 4.9m/s^{2}(7.4
s)^{2} = 268 m.

**Other Free Fall Exercises:**

**Free
Fall Exercises, Part One**

**Free
Fall Exercises, Part Two**

**To See the Free Fall Physics Theory:**

**Go To Free Fall
Theory**

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