1.

A sting breaks under a load of 4.8 kg A mass of 0.5 kg is attached to one end tothe string 2malong and is ratated in a horizontal circle caculate the greatest number of revolutions that the mass can make without breaking the string

Answer»

Solution :Given`m=0.5 kg`
`r=2 m`
`g=9.8ms^(-2)`
Themaximumtensionthat the stringcanwithstand
`F=4.8 kg wt=4.8xx 9.8 N`
LET themaximum NUMBER of revolutions persecond=v
Now F = `mr epsilon^(2)= mr (2 pi v)^(2) = 4PI^(2) mrv^(2)`
or `v^(2)=(F )/(4pi^(2)mr)`
`=(4.8 xx 9.8)/( 4xx 9.8 xx 0.5 xx 2) =1.215`
or `v = SQRT(1.215 )= 1.102 rps`
`=1.102 xx 60 =66 .13 rpm`


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