Which of the following equations illustrates the law of conservation of matter?
A. 2H2 + O2 + 2H20
B. 2H2 + 202 + 2H20
C. H2 + O2 + H2O
D. 2H2 + O2 + H2O

Under conditions for which the same room temperature is maintained by a heating or cooling system, it is not uncommon for a person to feel chilled in the winter but comfortable in the summer. provide a plausible explanation for this situation (with supporting calculations) by considering a room whose air temperature is maintained at 20â°c throughout the year, while the walls of the room are nominally at 27â°c and 14â°c in the summer and winter, respectively. the exposed surface of a person in the room may be assumed to be at a temperature of 32â°c throughout the year and to have an emissivity of 0.90. the coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 w/m2 â‹…â‹… k. what is the ratio of the thermal resistance due to convection to the thermal resistance due to radiation in the summer? what is the ratio of thermal resistances in the winter

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)

Choose a realistic problem for which these are the correct freebody diagrams. be sure that the answer that the problem requests is consistent with the diagrams shown. choose a realistic problem for which these are the correct freebody diagrams. be sure that the answer that the problem requests is consistent with the diagrams shown. a 1.0 kg block is placed on top of a 2.0 kg block. a horizontal rope pulls the 2.0 kg block across a frictionless floor with a force of 21.0 n. the coefficient between the two blocks is 0.75. does the 1.0 kg block on top slide?