Question
Download Solution PDFA block (of cross section 4 × 3 m size) of 20 kg mass rests on a flat horizontal surface as shown in figure below. If the coefficient of friction between the block and the surface is 1/4, the force 'F' which will cause block to move is approximately given by
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
Calculation:
Given:
\(\mathrm{m}=20 \mathrm{~kg}\ \mu=\frac{1}{4} \)
N = mg - F sin 30
= \(20 \times 10-\mathrm{F} \frac{1}{2}\)
= \(200-\frac{\mathrm{F}}{2}\)
Friction force \((f)=\mu N=\frac{1}{4}\left(200-\frac{F}{2}\right)\) = \(50-\frac{F}{8}\)
Condition for block to move
F cos 30 > friction force
\( \frac{F \sqrt{3}}{2}>50-\frac{F}{8} \)
\( F\left(\frac{\sqrt{3}}{2}+\frac{1}{8}\right)>50\)
F = 50.45 N
F > 5.04 kgf
Last updated on Apr 14, 2023
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