One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. having recently studied optics in your physics class, you're not too surprised to see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across, and you estimate that the distance from the window shade to the wall is about 3 m . estimate (a) the average wavelength of the sunlight (in nm) and (b) the diameter of the pinhole (in mm).

Asteam power plant operates on an ideal reheat rankine cycle between the pressure limits of 15 mpa and 10 kpa. the mass flow rate of steam through the cycle is 12 kg/s. steam enters both stages of the turbine at 500°c. if the moisture content of the steam at the exit of the low-pressure turbine is not to exceed 10 percent, determine (a) the pressure at which reheating takes place, (b) the total rate of heat input in the boiler, and (c) the thermal efficiency of the cycle. also, show the cycle on a t-s diagram with respect to the saturation lines. (2.15 mpa; 45.0 mw; 42.6%)

Idon’t quite understand this problem

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.