Apond is frozen over with a layer of ice 1.4 cm thick. the water under the ice is at 0∘c. the temperature of the air above the ice is −15∘c. this difference in temperature causes heat to flow through the ice from the water below to the air above. as heat is removed from the water, it freezes, adding to the thickness of the layer of ice. at what rate does the thickness of the ice layer increase? give the answer in centimeters per hour. you only need to consider the freezing of the water. you may neglect any additional cooling of the ice to temperatures below 0∘c.