Question

A 2 kg brick begins to slide over a surface which is inclined at an angle of 45° with respect to horizontal axis. The co-efficient of static friction between their surfaces is : 

(1) 1 

(2)  \(\frac{1}{\sqrt{3}}\)

(3) 0.5 

(4) 1.7

Answer 1

Correct option is : (1) 1

\(\mathrm{mg} \sin 45=\mathrm{f}_{\mathrm{L}}\)

mg cos 45 = N

\(\mathrm{f}_{\mathrm{L}}=\mu_{\mathrm{s}} \mathrm{N}\)

\(\mu_{\mathrm{s}}=\tan 45=1\)

or

\(\tan \theta=\mu_{\mathrm{s}}(\theta\ is\ \text{}angle \ of\ repose)\)

\(\tan 45=\mu_{\mathrm{s}}=1\)