Two children are throwing a ball back-and-forth straight across the back seat of a car. the ball is being thrown 9 mph relative to the car, and the car is travelling 45 mph down the road. if one child doesn't catch the ball and it flies out of the window, in what direction does the ball fly ? (ignoring wind resistance)

You have a resistor and a capacitor of unknown values. first, you charge the capacitor and discharge it through the resistor. by monitoring the capacitor voltage on an oscilloscope, you see that the voltage decays to half its initial value in 2.70 miss . you then use the resistor and capacitor to make a low-pass filter. what is the crossover frequency fc?