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A boy is moving on a straight road again...

A boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km, he forgot the correct path at a round about, of radius 100m. However, he moves on the circular path for one and half cycle and then he moves forward upto 2.0 km. Calculate the work done by him.

Text Solution

Verified by Experts

Given, force applied by boy against friction 5 = N
Displacement on the circular path=One cycle + Half cycled = 0 + Half cycle
`"=0+Diameter of circular path"" "(":.Displacement depends on initial and final point")`
`0+2r=0+2xx100" "[":'r=100m]`
`=0+200=200m`
`:.` Total displacements =1.5km+200+2.0km
`1.5xx100+200+2xx1000km" "(1km=1000m)`
`3700m`
`"Work done by boy" =F.dcostheta`
`=5xx3700xxcos0=18500J" "{:[(becausetheta=0^(@)),(thereforecos 0^(@)=1)]:}`
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