Q.

Consider a block kept on an inclined plane (inclined at 45°) as shown in the figure. If the force required to just push it up the incline is 2 times the force required to just prevent it from sliding down, the coefficient of friction between the block and the inclined plane (μ) is equal to                 [2023]

1 0.50  
2 0.33  
3 0.25  
4 0.60  

Ans.

(2)

F1=mgsin45°+f=mgsin45°+μN

F1=mg2+μmgcos45°

F1=mg2(1+μ)

F2=mgsin45°-f=mgsin45°-μN

                                    =mg2(1-μ)

F1=2F2

mg2(1+μ)=2mg2(1-μ)

1+μ=2-2μ

μ=130.33