You are tasked with calibrating the springs for a pinball machine. Your method of testing the springs is by attaching masses onto the end of the springs and measuring the stretch from initial position to final position. You hang a 14kg mass on a spring and notice that it stretches from 50 to 78cm. What is the spring constant for that spring

Acommercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°c by rejecting waste heat to cooling water that enters the condenser at 18°c at a rate of 0.25 kg/s and leaves at 26°c. the refrigerant enters the condenser at 1.2 mpa and 50°c. if the compressor consumes 3.3 kw of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the cop, and (d) the minimum power input to the compressor for the same refrigeration load.