A block moving with initial velocity u=20m/s comes to rest after covering distance of 40m on a rough plane. Find out coefficient of kinetic friction. (Take g=10m/s2)
A
0.5
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B
0.25
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C
0.75
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D
Data incomplete
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Solution
The correct option is A0.5 Given, u=20m/s S=40m
Using eq, v2=u2+2as 0−(20)2=2a×40 a=−5m/s2
Since no external force except friction is acting on the block, therefore
Frictional force = ma
= 5m
Also, friction force= μmg
therefore, μmg = 5m μg=5 μ=5g=0.5