Question

a 20 kg box is initially at rest with a static and kinetic friction of 0.40 is pushed with a force of 70 For 120 s. What is the work done?

Answer 1

$W=F\cdot s$

$F_{fr}=\mu mg=0.4\cdot 20\cdot 9.81=78.48N>70N$

This force ($70 N$) will not be able to move the box. So,

$s=0\to W=0$ Answer.