What is the velocity on impact of a ball dropped from a 20 m cliff?

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What is the velocity on impact of a ball dropped from a 20 m cliff?

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Answer 1 · 2016-01-22T20:28:39

$19.799 \frac{m}{s}$ $19.799m/s$

Explanation:

Data:-
Initial Velocity $= v_{i} = 0$ $=v_i=0$ (Because the ball is dropped not thrown)
Final Velocity $= v_{f} = ? ?$ $=v_f=??$
Height $= h = 20 m$ $=h=20 m$
Acceleration due to gravity $= g = 9.8 \frac{m}{s^{2}}$ $=g=9.8m/s^2$
Sol:-

Velocity on impact is the velocity of the ball when it hits the surface.

We know that:-

$2 g h = v_{f}^{2} - v_{i}^{2}$ $2gh=v_f^2-v_i^2$

$\Rightarrow v f^{2} = 2 g h + v^{2} = 2 \cdot 9.8 \cdot 20 + {(0)}^{2} = 392$ $implies vf^2=2gh+v^2=2*9.8*20+(0)^2=392$

$\Rightarrow v_{f}^{2} = 392$ $impliesv_f^2=392$

$\Rightarrow v_{f} = 19.799 \frac{m}{s}$ $implies v_f=19.799 m/s$

Hence, the velocity on imact is $19.799 \frac{m}{s}$ $19.799m/s$ .

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What is the velocity on impact of a ball dropped from a 20 m cliff?

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