Ongoing Energy

Today was B Block's chance to run an investigation on conservation of energy. By observing an oscillating spring and making measurements of the kinetic energy and elastic potential energy, it was clear that the total energy was conserved nicely in this system. Attaching an index card to piece of paper to the bottom of the spring made friction a significant force and conservation of mechanical energy was not observed. Concentrate on your conclusion for your write-up tonight - the patterns of the energy conversions, the adherence to conservation of energy, etc. We'll discuss the lab tomorrow and then wrap up ideas with energy conservation and power.

C and F Blocks discussed the idea of power. The word has its own meaning in daily life and that meaning bears no real resemblance to the scientific use - the rate of energy conversion or the rate at which work is performed. Two machines with different power ratings can absolutely do the same work - the lower-power machine just takes longer. We emphasized that the unit - the Watt - that we see on light bulbs and appliances is the same Watt as for our mechanical energy studies and took some time to observe the power of three computers and a television set. For your poor old parents, remember that electrical power reports the rate of energy consumption by your electronics and every Joule of that energy ends up on the electric bill... tomorrow, we'll go over your power homework problems and review for Monday's exam. Then, it's off to momentum!

E Block strolled through conservation of energy, using their lab focused on energy of a ball thrown into the air as an example. The total energy was nicely conserved in that system, although the energy was continually being converted between gravitational potential and kinetic. When the ball was bounced on the floor, however, conservation of mechanical energy faltered. There was significant loss to non-mechanical forms and the overall energy declined with each bounce. We'll go over your conservation of energy problems tomorrow, then move into power.