Question

5) A box of mass 25 kg is dragged across a level floor by a rope that makes an angle of 25^o above the horizontal. The coefficient of friction between the box and the floor is 0.72. Find the force F that will ensure the box moves with constant speed.

Answer 1

Answer 2

use:
F cos(25) = miu*m*g
F *cos(25)= 0.72*25*9.8
F=194.6 N

Ans: 194.6 N

Answer 3

The sum of the forces in horizontal direction is zero

$FCos\theta -f_{k}=0$

$FCos\theta=\mu_{K}N=\mu _{K}(mg-Fsin\theta )$

$F=\frac{\mu _{k}mg}{Cos\theta +\mu _{k}Sin\theta }$

F=0.72*25*9.8/(Cos25+0.72*sin25)

F=145.7 N