1.

A stone is dropped from the top of a tower of height `h`. Aftre `1 s` another stone is droppped from the balcony `20 m` below the top. Both reach the bottom simultaneously. What is the value of `h` ? Take `g=10 ms^(-2)`.A. 43125mB. 312.5mC. 31.25mD. 25.31m

Answer» Correct Answer - C
`h=(1)/(2)"gt"^(2)` and `h-20=(1)/(2)g(t-1)^(2)`
`(1)/(2)"gt"^(2)-20=(1)/(2)"gt"^(2)-20=(1)/(2)"gt"^(2)-gt+(g)/(2)`
`gt=20+(g)/(2)`
`10t=20+5rArr t=2.5`
`h=(1)/(2)"gt"^(2)=(1)/(2)xx10xx(2.5)^(2)`
`=5xx6.25=31.25m`


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