Question

In the track shown in figure section AB is a quadrant of a circle of 1 metre radius. A block is released at A and slides without friction until it reaches B. After B it moves on a rough horizontal floor and comes to rest at distance 3 metres from B. What is the coefficient of friction between floor and body?

• A. $1/3$
• B. $2/3$
• C. $1/4$
• D. $3/8$

Answer 1

Answer: (A)

$m g l = \frac{1}{2} m u^{2}$
$\Rightarrow u^{2}=2 g\,\,\,(i)$
$v^{2} \equiv u^{2}+2 a s$
$\Rightarrow 0=2 g-2 a(3)$
$\Rightarrow a=\frac{g}{3}$
$\Rightarrow \mu_{k} g=a$
$\therefore \mu_{k} g=\frac{g}{3}$
$\therefore \mu_{k}=\frac{1}{3}$