DSLR

The fundamental problem with dSLRs is that it has a moving mechanical component which adds to the vibration.  Why have a separate viewfinder and the whole swiveling lens mechanism when you can just see the image you are about to capture on the LCD?  Still, most of the experienced users swear that they will never buy a camera without a viewfinder.  Alas, as Max Planck pointed out, the only way for new ideas to get accepted is for old proponents to die. I look forward to the day non-SLR cameras have all the advanced features that go into a dSLR without the drawback of the movable prism.

Things that don’t work

There are a lot of technologies that keep coming up as solutions to various problems.  A popular one is generation of energy from waste matter.  What people forget is that gasoline has an incredible energy density.  This reminds me of the quote about making a small fortune–first start with a large fortune.  It is estimated that in order to get enough biogas for one person’s cooking needs, from food waste, it takes the garbage of 200 people.  Naturally, the cost of the food for all these people far exceeds the amount of fuel thus generated.  When these fuels do become economical, i.e., when the fossil fuels are exhausted, the resulting economic collapse would have made things like transportation fuel superfluous.

Another aspect of biogas that is not considered is the safety of the system. Whereas this was at one time thought to be useful for generating small amount of fuel in rural areas, the current green thought has it moving into urban (read high density) areas too. There are even small units which are marketed to apartment dwellers (to place inside an enclosed space)!! There is not much of a phase of development for these kind of systems that can be called “design”. Most likely, it starts with an idea by a non technical person and develops without review by any experienced engineer. The people who market these glibly ignore the dangers posed by explosive gas mixtures.

Another idea is that of using solar energy to drive an automobile.  This is touted as some kind of super vehicle which gives unlimited energy.  Simple calculations show that it is difficult to get even near a kilowatt for such a vehicle (considering solar cell efficiencies and the solar constant, which is about 1 kW/m^2).  However you reduce the weight  of the vehicle, you end up with the mass of the driver, and all this fragile device can now do is putter around on level ground.  Notice that the average consumer vehicle uses less than 5% of its rated power at cruising speed.  The rest of the power is for drivability.

Geothermal energy is a really small fraction of the solar energy that comes in. Compared to the average power of 6000TW from the sun, the energy flux from inside the earth is just around 50TW. An average power plant produces around 2 GW of power. So this power, that is spread over all of earth is comparable to some man made power source. What we can do is to dig deep and access the region of earth which will be at a constant temperature, equal to the average temperature of the local region, and use it for air conditioning. This method was used extensively by Romans–they had a tunnel dug under the house and and opening in the roof. The convection currents thus set up would remove hot air and bring in cold air.

Wind power is another non-starter. For large scale wind turbines that produce megawatts of power, this is not true. However, for small wind turbines, power generation considering frictional losses and repair costs is approximately zero in most locations of the world. A major study of home wind energy generation was conducted in the UK for a period of one year at several locations in 2007-2008. It was found that the claims of the wind turbine manufacturers were vastly exaggerated. Most of the turbines did not generate enough power to cover the power taken by the electronics. On the other hand, high power producing turbines had to be shut down as other residents objected to the noise!! The reliability of the wind turbines was a major issue, with the inexperience of the companies involved being exposed in the test. Note that an automobile engine produced in a high tech factory with the latest tools and technology is rated to only a few thousands hours of use before overhaul. It is perhaps too much to expect more from wind turbines.

Effect of Earth’s rotation on a golf shot

The effect of Earth’s rotation on a 300 yard shot is given by the Coriolis acceleration. For a range of 300 yards, the ball should have an initial speed of 50 m/s. The value of angular velocity for Earth is about 10^-5. This gives a Coriolis acceleration of 10^-2 m/s^2. The total deflection is given by the time of flight, which is about 10 seconds, is of the order of 1m, which is quite a surprising result.