A square threaded screw is used to lift a load W by applying a force F. Efficiency of square threaded screw is expressed as

A single – plate clutch has a friction disc with inner and outer radii of $$20mm$$ and $$40$$ $$mm,$$ respectively. The friction lining in the disc is made in such a way that the coefficient of friction $$\mu $$ varies radially as $$ = 0.01\,r,$$ where $$r$$ is in $$mm.$$ The clutch needs to transmit a friction torque of $$18.85$$ $$kN.mm.$$ As per uniform pressure theory, the pressure (in $$MPa$$) on the disc is ___________________.

For the brake shown in the figure, which one of the following is TRUE?

The force $${F_1}$$ and $${F_2}$$ in a brake band and the direction of rotation of the drum are as shown in the figure. The coefficient of friction is $$0.25.$$ The angle of wrap is $$3\pi /2$$ radians. It is given that $$R=1$$ $$m$$ and $${F_2} = 1N.$$ The torque (in $$N-m$$) exerted on the drum is ____________