Question

When a person walks on the ground the work done by the friction force is zero?

Answer 1

yez it iz so because work is equal to force multiplked by displacement and if any one of it is zero then work is also zero now friction force is only present when the foot of the person touches ground at this instant force is not zero but displacement is zero so workis also zero now when person lifts leg from ground to move leg forward then at this instant displacemwnt is not zero but frictional force is not present so frictionla force is zero so again work is zero...

hope you get it ...