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## Homework Statement

Two rocks are falling from a roof. The second one begins its fall when the first one has already covered 30cm. Calculate the distance d between these two rocks after 10 seconds counted from the moment the second rock begins its fall.

## Homework Equations

[itex]s=s_{0}+v_{0}t+\frac{at^{2}}{2}[/itex]

[itex]v(t) = v_0 + at[/itex]

## The Attempt at a Solution

It turns out second rock will go as follows: [itex]s_2=\frac{at^2}{2}={9,81*100}{2}\approx 490,5m[/itex]. If it does, then we have [itex]0,3=\frac{9,81t^2}{2}[/itex] so [itex]t\approx0,25s[/itex]. Then, we know that [itex]v(0,25)=0+9,81*0,25=2,4525m/s[/itex]. And finally [itex]s_1=0,3m+2,45*10+\frac{9,81\cdot100}{2}=515,3m[/itex] so they're 24,8 metres apart. Is that OK?