A chef, upon awaking one morning to find his stove out of order, decides to boil the water for his wife's coffee by shaking it in a thermos flask. Suppose that he uses 1/2 liter of tap water at 59o C, and that the water falls 40 cm each shake, and the chef making 30 shakes each minute. Neglecting any heat loss to the room, how long must he shake the flask before the water boils?