Question

Coefficient of friction between a tool and grinding wheel is μ.Power developed in watt by the wheel of radius r running at n revolutions per second when tool is pressed to the wheel with F' kgf is

• A. μF'r(2πn)
• B. μF' gr(2πn)
• C. μF'r
• D. μF'g

Answer 1

Answer: (B)

μF' gr(2πn)

Answer 2

Using P = Fv, we get

P = Frω ( v = rω)

Here F = μN

(where N is normal reaction)

= μF'g ( 1 kgf = g newton)

∴ P = μF'grw = 2πμnF'gr

( ω = 2πr)