Calculate the efficiency of a hair dryer which takes in 3000J of energy per second and transfers 600J as useful heat energy. Calculate the efficiency of the hair dryer.

The efficiency of the hair dryer is 0.2 or 20%

Explanation:

The efficiency of a machine or any appliance is a measure of the useful work done by the machine when an effort is applied to the machine. The higher the efficiency of a machine, the more useful work the machine does.

Due to the economical and environmental impact of energy production, machines and appliances of high efficiency are being developed and recommended for domestic as well as industrial use nowadays.

In electrical appliances, energy is usually supplied by electrical power units. The higher the efficiency of an electrical appliance, the less power it consumes to do useful work. For a hair dryer which takes in 3000 J of energy per second and transfers 600 J of useful heat energy, its efficiency is calculated with formula below:

efficiency = useful energy / total energy input

Efficiency = 600 J / 3000 J = 0.2

Therefore, the efficiency of the hair dryer is 0.2 or 20%

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

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