There are four samples P, Q, R and S, with natural frequencies 64, 96, 128 and 256 Hz, respectively. There are mounted on test setups for conducting vibration experiments. If a loud pure not of frequency 144Hz is produced by some instrument, which of the samples will show the most perceptible induced vibration?

In the velocity diagram shown below, $$u=$$ blade velocity, $$C=$$ absolute fluid velocity and $$W = $$ relative velocity of fluid and the subscripts $$1$$ and $$2$$ refer to inlet and outlet.

A vapor absorption refrigeration system is a heat pump with three thermal reservoirs as shown in the figure. A refrigeration effect of $$100$$ $$W$$ is required at $$250$$ $$K$$ when the heat source available is at $$400$$ $$K.$$ Heat rejection occurs at $$300$$ $$K.$$ The minimum value of heat required (in $$W$$) is

The following four figures have been drawn to represent a fictitious thermodynamic cycle, on the $$P$$-$$v$$ and $$T$$-$$S$$ plates

According to the first law of thermodynamics, equal areas are enclosed by