free fall

Question

A stone is dropped from the top of a tower 80 m high. How long will it take to reach the ground? (g = 10 m/s²)

RankGuru · Accepted Answer

1. **Motion Characteristics**: Free fall from rest implies $u=0$ and acceleration $g=10$ m/s$^2$.
2. **Equation**: $h = \frac{1}{2}gt^2$.
3. **Calculation**:
   - $80 = \frac{1}{2} 	imes 10 	imes t^2$.
   - $80 = 5t^2$.
   - $t^2 = 16$.
4. **Result**: $t = 4$ seconds.

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