Question

(13%) Problem 4: A stone is dropped from rest from the top of a cliff for it to reach the ground. . ft takes 47 s

Answer 1

Part (a)

Since the stone is dropped and not thrown,initial velocity is zero

ANSWER: ${\color{Red} v_{i}=0m/s}$

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Part (b)

There are no external forces acting on the stone, it is falling under influence of gravity

so acceleration is equal to acceleration due to gravity

$a=g$

ANSWER: ${\color{Red} a=9.81m/s^{2}}$

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Part (c)

Use formula $v=u+at$

ANSWER: ${\color{Red} v_{f}=v_{i}+a*\Delta t}$

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Part (d)

$v_{f}=v_{i}+a*\Delta t$

$v_{f}=0m/s+9.81m/s^{2}*4.7s$

ANSWER: ${\color{Red} v_{f}=46.107m/s}$

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Part (e)

Use formula $s=ut+1/2at^{2}$

ANSWER: ${\color{Red} \Delta y=v_{i}*\Delta t+1/2a*\Delta t^{2}}$

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Part (f)

$\Delta y=v_{i}*\Delta t+1/2a*\Delta t^{2}$

$\Delta y=0m/s*4.7s+1/2*9.81m/s^{2}*(4.7s)^{2}$

$\Delta y=0+0.5*9.81*4.7^{2}$

ANSWER: ${\color{Red} \Delta y=108.35m}$

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