Một lò xo có độ cứng k = 25 N/m, chiều dài tự nhiên l0 = 1,00m được chập làm đôi. Hai đầu buộc chung vào một điểm treo, điểm chính giữa buộc quả nặng nhỏ khối lượng m = 250 g. Quả nặng được cấp năng lượng ban đầu W0 = 20 mJ. Chọn t0 = 0 là lúc quả nặng qua vị trí cân bằng theo chiều dương trục Ox. Phương trình của gia tốc a(t) là:

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.

Which of the following statements comparing electron microscopy and light microscopy is false? which of the following statements comparing electron microscopy and light microscopy is false? both the electron microscope and the light microscope use the same wavelengths for illumination. images produced by light microscopes can be in color, whereas electron microscope images are black and white unless they are artificially colored. the electron microscope has greater resolution than the light microscope. electron microscopes can allow examination of viruses and internal cell structures, whereas light microscopes are limited to objects that are 0.5 micrometers and larger. request answer

Compare the maximum rate of heat transfer to the basal metabolic rate by converting a bmr of 88 kcal/hr into watts. what is the value? from this comparison you should see why the body can accommodate a modes amount of activity in hot weather but strenuous activity would increase the metabolic rate above the body's ability to remove heat [12].