first part is correct, second part is incorrect.
Hint: Since N has increased, f has to increase
An 80N wooden block is placed on top of a wooden table.If a force of 28N is necessary to keep the block moving at a constant velocity.
a)What is the co-efficient of sliding friction for the wooded block?
b)if a wieght of 40N is placed on top of the wooden block what force will be required at a constant velocity across the table?
f=28 , N=80
Am I correct?