# Physics

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Earthquakes are essentially sound waves travelling through the earth. They are called seismic waves. Because the earth is solid, it can support both longitudinal and transverse sismic waves, which travel at different speeds. The speed of longitudinal waves, called P waves, is 7274.0 m/s. Transverse waves, called S waves, travel at a slower 3803.0 m/s. A seismograph records the two waves from a distant earthquake. If the S wave arrives 4.47 min after the P wave, how far away was the earthquake? You can assume that the waves travel in straight lines, although actual seismic waves follow more complex routes.

• Physics -

A battery of three cells in series each of emf 2v and internal 0.5 ohms is connected to two ohms resistors in series with a parallel combination of two 3ohms resistors? (a) draw the circult diagram (b)the effecive of ex ternal resistance (c)the current in the circult (d)the lost volt in the battery (e)the current in one of the three ohms resistor.