1.

A moving snowball is completely melted by its impact against a wall. The speed (in ms^(-1)) of snow ball is:

Answer»

`8 cdot 2xx10^(2) m//s`
`2 cdot 1 xx10^(2) m//sec`
`16 cdot 4 xx10^(2) m//s`
None of the above.

Solution :Let m be the mass and v be the speed of ice BALL.
`therefore` Work done `W=(1)/(2) MV^(2)`
Heat PRODUCED `Q=(W)/(J) =(mv^(2))/(2J)`
Heat REQUIRED to melt ice ball Q.=mL
`therefore (mv^(2))/(2J) =mL rArr v=sqrt(2JL)`
`=sqrt(2xx4 cdot 2xx80xx10^(3))=8 cdot 19 xx10^(2) m//s`.
`=8 cdot 2xx10^(2) m//s`.
Thus, correct choice is (a).


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