An airplane flies 700 miles with a tail wind in 2.0 hrs. if it takes 2.5 hrs to cover the same distance against the headwind, then what is the speed of the plane in still air? a).290mph b).315mph c).240mph d).330mph e).250mph

An insulated thermos contains 148 g of water at 72.7 ˚c. you put in a 11.7 g ice cube at 0.00 ˚c to form a system of ice + original water. the specific heat of liquid water is 4190 j/kg•k; and the heat of fusion of water is 333 kj/kg. what is the net entropy change of the system from then until the system reaches the final (equilibrium) temperature?