A coin is kept at a distance 10 cm from the centre of turn table of ra

1.	A coin is kept at a distance 10 cm from the centre of turn table of radius 1 m just begins to slip, when the turn table rotates at speed of 90 r. p. m. Calculate the coefficient of static friction between coin and the turntable. ( g = 9.8 m/s2).
Answer» Given, r = 10 cm = 0.1 m radius at which it steps, Centrifugal force = Remaining static friction ⇒ μ_smg = mrω² ω = 90rpm = \(\frac{90\times 2\pi}{60}\) rad/s = 1.5 x 2π = 3π rad/s ⇒ μ_s x m x 9.8 = m x 0.1 x 9π² ⇒ μ_s= \(\frac{0.1\times 9 \times 9.8}{9.8}\) = 0.9

A coin is kept at a distance 10 cm from the centre of turn table of radius 1 m just begins to slip, when the turn table rotates at speed of 90 r. p. m. Calculate the coefficient of static friction between coin and the turntable. ( g = 9.8 m/s2).

Answer»

Given,

r = 10 cm = 0.1 m

radius at which it steps,

Centrifugal force = Remaining static friction

⇒ μ_smg = mrω²

ω = 90rpm

= \(\frac{90\times 2\pi}{60}\) rad/s

= 1.5 x 2π

= 3π rad/s

⇒ μ_s x m x 9.8 = m x 0.1 x 9π²

⇒ μ_s= \(\frac{0.1\times 9 \times 9.8}{9.8}\)

= 0.9