A car sounds its horn while approaching an observer at 20 m/s. If the observer hears a frequency of 430 Hz, find the frequency emitted by the car's horn. Assume the speed of sound is 343 m/s.

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?

Aseries circuit contains a 30 e resistor, a 20 resistor, and a 10 resistor. the power supply provides 100 v to the circuit the current in the 10 resistor, to two significant figures, is a.

Five renewable energy resources are wind, sunlight, moving water and geothermal energy. question 2 options: true false