In class, we performed a series of experiments testing the relationship between mass, acceleration, and power. We designed the experiment using a pulley, strong, set of weights, and motor. The string attached to a motor on one side of the pulley, wrapping around it as a wheel turns. On the other side of the pulley the strong is attached to a hook that can hold weights.
For the first experiment we tested a fixed mass vs. modified power levels. We kept the mass constant at .19 kg for 4 trials. The power level began at 25%. The motor turned on, causing the string to wrap around the wheel and pull up the weights. There was an acceleration of 2.57 rpm/s. We conducted 3 more trials, increasing the power level by 25% each time. The results can be seen in the graph below:
For our second experiment we tested a fixed power level vs. modified masses. We kept the power level constant at 75%. We first texted this power level pulling a mass of .25 kg. The acceleration was 48.49 rpm/s. We conducted 3 more trials with masses of .21 kg, .17 kg, and .13 kg, respectively. The results can be see in the graph below:
danaress
February 7, 2012
The Automobile Industry is under increasing pressure each year to improve the fuel efficiency of their cars. The Corporate Average Fuel Economy (CAFE) are the federal regulations that control exactly what standards automobile manufacturers are held to. Under President Obama, the new standard has been set at reaching an average gas mileage at 35.5 mpg by 2016. By 2025 the standard is 61 mpg for smaller passenger cars, and 30 mpg for the larger class of light trucks. These standards will most likely be raised over the years as technology improves.
The most promising technology being used to increase gas mileage in automobiles is hybrid vehicles. A hybrid vehicle is a vehicle that “combines two or more sources of power that can directly or indirectly provide propulsion power.” There are two basic types of gasoline-electric hybrid systems.
Parallel Hybrids use gasoline engines and electric motors to power the car. The electric motor gets much of its power from regenerative brake systems. These work, in very simplistic terms, by converting kinetic energy into usable electric energy. The gasoline engine also powers the transmission that turns the wheels. These vehicles have advanced computers in them that control all of these operating systems and make sure they are working efficiently together.
The other system used in hybrid vehicles is called Series Hybrid. This system uses a gasoline engine to supply power to a generator, which then powers the battery and electric engine. Only the electric engine directly powers the wheels turning.
These two systems have great potential for improvement. As more and more companies are producing hybrid vehicles, the amount of research and development is always increasing. The computer systems that are designed to maximize efficiency will become more advanced and better at their jobs. The engines themselves will be built lighter and more compact. They will become more efficient at converting energy into electric power. These improvements are inevitable. The continued pressure from the federal government gives the car companies the formal incentive, or perhaps negative incentives, to do so. They will in turn be saving consumer money on fuel costs, contributing to our energy independence, and reducing our greenhouse gas emissions. It is truly win-win for all parties involved.
danaress
February 7, 2012
