Question

a force of 20 newton is applied on a block but the block does not move what is frictional force on the block option is 20 Newton option be less than 20 Newton option see more than 20 Newton of CMD depends on roughness of blocking table

Answer 1

hi friend
here's your answer looking for

if the force of 20 newton is applied on the block , but the block doesn't move.
that means there work done is zero because there is not displacement. there is not displacement

and if the 20 newton is applied to the block then there must be the equal and opposite 20 Newton frictional force that is applied to that block.
because this will cancel out each other and give the net force equal to zero.

so, Option A is correct 20 N of frictional force.

hope you are satisfied with my answer