Suppose there are two finned heat sinks with identical geometry. One is made of copper and one out of aluminum. Assume that copper has approximately twice the thermal conductivity of aluminum. The flat side of the heat sink is attached to a constant temperature source, which we can call the hot side. Assume the hot side is held at 100C. On the cold (finned) side air is being forced over the fins. Under what condition would the heat sinks transfer heat at closest to the same rate? a) 40C air is forced slowly over the fins. b) 40C air is forced quickly over the fins. c) 50C air is forced slowly over the fins. d) 50C air is forced quickly over the fins.

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?