Question 1161026
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In Physics, they write the Energy conservation equation


    {{{(mv^2)/2}}} = mgh     (1)


and then obtain from this formula (after canceling the mass "m" in both sides)


    v = {{{sqrt(2gh)}}}.      (2)


According to formula (2)


    v = {{{sqrt(2*9.81*20)}}} = {{{sqrt(392.4)}}} = 19.81 m/s.


You can round it to 20 m/s.
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