Free fall

How long does the stone fall freely into a depth of 80m? What speed will it hit the bottom of the abyss?

Result

t =  4 s
v =  40 m/s

Solution:

s=12gt2 g=10 m/s2 s=80 m t=2 sg=2 8010=4 ss=\dfrac{ 1 }{ 2 } g t^2 \ \\ g=10 \ \text{m/s}^2 \ \\ s=80 \ \text{m} \ \\ t=\sqrt{ \dfrac{ 2 \cdot \ s }{ g } }=\sqrt{ \dfrac{ 2 \cdot \ 80 }{ 10 } }=4 \ \text{s}
v=g t=10 4=40 m/sv=g \cdot \ t=10 \cdot \ 4=40 \ \text{m/s}



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