A state highway patrol car radar unit uses a frequency of 9.00 * 109 Hz. What frequency difference will the unit detect from a car approaching a parked patrol car with a speed of 28.6 m>s

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.

Another word for electromagnetic energy is a. heat b. force c. matter d. radiation