Aheat pump with a cop of 3.2 is used to heat a perfectly sealed house (no air leaks). the entire mass within the house (air, furniture, etc.) is equivalent to 1200 kg of air. when running, the heat pump consumes electric power at a rate of 5 kw. the temperature of the house was 7∘c when the heat pump was turned on. if heat transfer through the envelope of the house (walls, roof, etc.) is negligible, the length of time the heat pump must run to raise the temperature of the entire contents of the house to 22∘c is a. 13.5 min b. 43.1 min c. 138 min d. 18.8 min e. 808 min

Tom is having a problem with his washing machine. he notices that the machine vibrates violently at a frequency of 1500 rpm due to an unknown rotating unbalance. the machine is mounted on 4 springs each having a stiffness of 10 kn/m. tom wishes to add an undamped vibration absorber attached by a spring under the machine the machine working frequency ranges between 800 rpm to 2000 rpm and its total mass while loaded is assumed to be 80 kg a) what should be the mass of the absorber added to the machine so that the natural frequency falls outside the working range? b) after a first trial of an absorber using a mass of 35 kg, the amplitude of the oscillation was found to be 10 cm. what is the value of the rotating unbalance? c) using me-3.5 kg.m, find the optimal absorber (by minimizing its mass). what would be the amplitude of the oscillation of the absorber?