Two boats start together and race across a 68-km-wide lake and back. boat a goes across at 68 km/h and returns at 68 km/h. boat b goes across at 34 km/h, and its crew, realizing how far behind it is getting, returns at 102 km/h. turnaround times are negligible, and the boat that completes the round trip first wins.

Diamond will scratch quartz. true or false

Find the dimensions and area of the largest rectangle that can be inscribed in the upper half of the ellipse. (give your answers in terms of a and b. enter the dimensions as a comma-separated list.)

An ice-making machine inside a refrigerator operates in a carnot cycle. it takes heat from liquid water at 0.0 degrees celsius and rejects heat to a room at a temperature of 19.2 degrees celsius. suppose that liquid water with a mass of 76.3kg at 0.0 degrees celsius is converted to ice at the same temperature. take the heat of fusion for water to be l_f = 3.34*10^5 j/kg. how much energy e must be supplied to the device? express your answer in joules.