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ID: 1353259 • Letter: H
Question
home / study / questions and answers / science / physics / a rock is dropped from a 18 m -high ledge. what's ... Your question has been answered! Rate it below. Let us know if you got a helpful answer. Question A rock is dropped from a 18 m -high ledge. What's its speed when it hits the ground? Express your answer to two significant figures and include the appropriate units. I got -19 m/s and this worked. Now... What's its height when its speed is half the value found in previous part? Express your answer to two significant figures and include the appropriate units. I got 4.6 m but this is not the right answer
Explanation / Answer
When an object undergoes free fall from rest, its speed when it hits ground is
v= sqrt(2gh)
= sqrt(2*9.8*18)
v= 18.78 m/s
when it speed is half the value, then
18.78/2= sqrt(2*g*h2)
h2= 4.4985 m
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