Question

a 4 kg block is being pulled by a string at a constant speed on a surface with coeficient of kinetic friction of .3. If the string is at an angle 45 degrees above the horizontal, what is the magnitude of the force F(also known as the string)?
Elena
0= - mg+N+Fsinα => N=mg-Fsinα
=> F(fr) =μN =μ(mg-Fsinα)
ma=Fcosα-F(fr) = Fcosα - μ(mg-Fsinα)
a=0
Fcosα =μmg- μFsinα
F(cosα + μsinα)=μmg
F= μmg/(cosα + μsinα)= …