Professional Application A 30,000-kg freight car is coasting at 0.850 m/s with negligible friction under a hopper that dumps 110,000 kg of scrap metal into it. (a) What is the final velocity of the loaded freight car? (b) How much kinetic energy is lost?
BIOL 300 Foundations of Biology – Telleen Section 3 pt 4 1. Heat storage – temperature is a measure of how rapidly individual molecules are moving. Due to H-bonds, H2O requires lots of energy to disrupt its organization. Thus, it takes lots of energy to heat, heats slowly, and holds temperature longer than most other molecules. This is why we can maintain a relatively stable body temperature 2. Ice formation – at low temperatures H-bonds don’t break easily resulting in a crystal structure. Interestingly, solid water (ice) is actually less dense than liquid water (this is why a beer can will explode if you put it in the freezer for too long!) 3. High heat of vaporization – Since an increase in temperature is required to break the H-bonds in water, the liquid to vapor transition takes lots of energy. This is why sweating cools us off (i.e. there is a net loss of energy, which we perceive as a lower temperature, as the sweat evaporates into the air). 4. Cohesion is the attraction between individual water molecules, due to their polarity and the H-bonds. As result, one water molecule can pull another (which can pull another, and so on). This results in surface tension and capillary action, which both play important roles in biology. Cohesion is the attraction (through H-bonds) between the same type of molecule (e.g. H2O with H2O), while adhesion refers to H-bonding and attraction between different types of molecules (e.g. H2O and NH3).