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Two identical blocks of ice move in opposite directions with equal speed and collide with each other. What will be minimum speed required to make both the blocks melt completely, if the initial temperatures of the blocks were -8^@ C each? Specific heat of ice is 2100 J kg^(-1) K and latent heat of fusion of ice is 3.36 xx 10^5 J kg^(-1) |
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Answer» `840 ms^(-1)`  whenthe identicalblockcollidewith eachotherthenthhelossin kineticenergywill beequalto thethermalenergygainedby them. ` therefore ` Lossin K.E =`1/2 muv^2 rel` `=1/2 [(m_1 m_2 )/( (m_1+m_2))] (v_1-v_2) ^2= 1/2 [(m XX m )/((m + m))] [u-(-u ) ]^2` ` (:.m_1= m_2 = m, v_1=u andv_2=- u)` `=1/2[(m^2 )/( 2m ) ](2u)^2=1/2 xx (m/2)xx 4 u^2 = mu^2` Lossin K.E `=(msDeltaTheta+ m L ) xx 2 ` `impliesmu ^2=- 2m ( sDelta+ m L) xx 2` `implies m u^2= 2m (sDelta theta+L) implies U^2= 2 ( s Deltatheta+L )` `impliesu= sqrt(2 (s Delta+L))` ` impliesu=sqrt(2 [(2100 xx 8) + 3.36 xx 10^5 ])impliesu= 840 m//s` |
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