1) The middle-C hammer of a piano hits two strings, producing beats of 1.45 Hz. One of the strings is turned to 270.00 Hz. What frequencies (in Hz) could the other string have? (Answer to the nearest 0.1 Hz.)
lower possible frequency _________Hz
Higher possible frequency_________Hz
2) Suppose you have a device that extracts energy from ocean breakers in direct proportion to their intensity. If the device produces 12.0 kW of power on a day when the breakers are 1.20 m high, how much (in kW) will it produce when they are 0.400 m high?
___________kW
3) Energy from the Sun arrives at the top of the Earth's atmosphere with an intensity of 1.30 kW/m2. How long does it take for 2.03 109 J of energy to arrive on an area of 1.00 m2? This is the average monthly electrical energy consumption of a family of four in the United States.
___________hr