Answers

2015-04-12T14:15:01+05:30
WORKDONE DOESNOT HAPPENS ON THE ANT SINCE IT DOESNOT HAVE ANY DISPLACEMENT WHILE IT SIT ON THE BACK OF THE MICE SO
      W=F*S
        =F*0  [S=0]
       =0
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2015-04-12T14:29:41+05:30
Force should be accent on the object or the object must be displaced.
 These are the two conditions for work said to be done.
In this case , only the mice is doing the work,
work of the ant is , W=F*S
                              W=0

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in this case...force is perpendicular to displacement...so...w=s*fcos90
ant's weight is vertically downward I.e.,force.....and mice displacement is horizontal....which is perpendicular to force.....so....w=s×fcos90=0