question_answer

Two stones are released from rest one from a height of 20 m and another from some unknown height above the ground. One of the stones hits the ground 1s after the other strikes the ground. The height from which the second stone is released can have values of______. \[(~\text{g}=\text{1}0\text{ m}{{\text{s}}^{-\text{2}}})\]

Answer:

  Time taken by the first stone is \[=20=\frac{1}{2}\times 10\times {{t}^{2}}\] \[\Rightarrow {{t}^{2}}=\frac{20}{5}\Rightarrow t=2s\] \[{{h}_{1}}=\frac{1}{2}\times 10\times {{3}^{2}}=\frac{1}{2}\times 10\times 9=45m\] \[{{h}_{2}}=\frac{1}{2}\times 10\times {{(t-1)}^{2}}\] \[=\frac{1}{2}\times 10\times {{(1)}^{2}}=5m\]