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A ball is thrown downwards with a speed ...

A ball is thrown downwards with a speed of `20m//s` from top of a building 150m high and simultaneously another ball is thrown vertically upwards with a speed of `30m//s` from the foot of the building . Find the time when both the balls will meet . `(g=10m//s^(2))`

Text Solution

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(i)`S_(1)=20t+5t^(2)+S_(2)=30t-5t^(2)`
`150=50t`
`t=3s`.

(ii)Relative acceleration of both is zero since both have acceleration in downward direction.
`veca_(AB)=veca_(A)-veca_(B)=g-g=0`
`vecV_(BA)=30-(-20)=50`
`S_(BA)=V_(BA)xxt`
`t=(S_(BA))/(V_(BA))=(150)/(50)=3s`
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