Compute the speed of sound waves in air at room temperature 20°C. Given, the mean molar mass of air is 28.8 gram/mol, the ratio of heat capacities 1.40 and R= 8.314 J/mol-k.

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?