Question

Consider a block kept on an inclined plane (inclined at $45^{\circ}$ ) 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 inclined plane $(\mu)$ is equal to :

• A. $0.50$
• B. $0.33$
• C. $0.25$
• D. $0.60$

Answer 1

Answer: (B)

$0.33$

Answer 2

The correct answer is (B) : 0.33

F1​=mgsin45∘+f=mgsin45∘+μN
F1​=2​mg​+μmgcos45∘
F1​=2​mg​(1+μ)

F2​=mgsin45∘−f=mgsin45∘−μN
=2​mg​(1−μ)
F1​=2F2​
2​mg​(1+μ)=22​mg​(1−μ)
1+μ=2−2μ
μ=1/3=0.33