If an object just begins to slide on a surface inclined at 30^o to the horizontal,the coefficient of friction is

Water does not drop through an open umbrella of silk materials unless the inside of the umbrella is touched. This is due to

The stylus of a phonograph record exerts a force of 7.7 x 10^-2N on a groove of radius 10^-5m. Compute the pressure exerted by the stylus on the groove

A piece of stone attached to one end of a string is whirled round in a horizontal circle and the string suddenly cuts. The stone will fly off in a direction

A 90cm uniform lever has a load of 30N suspended at 15cm from one of its ends. If the fulcrum is at the center of gravity, the force that must be applied at its other end to keep it in horizontal equilibrium is