A 900-kg boat is travelling at 70 km/hr when its engine is shut off. The magnitude of the frictional force fk between the boat and water is proportional to the speed of the boat by
fx = -30v, where v is in m/s and fk in N. Find the time required for the boat to slow down
to 35 km/ hr.​

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.