3. Two strings with linear densities of 5.0 g/m are stretched over pulleys, adjusted to have vibrating lengths of 50 cm, and attached to hanging blocks. The block attached to string 1 has a mass of 20 kg and the block attached to wire 2 has mass M. Listeners hear a beat frequency of 2.0 Hz when wire 1 is excited at its fundamental equency and wire 2 at its third harmonic. What is one possible value for mass M? 4. Two loudspeakers emit sound waves alond the xaxis. The sound has maximum intensity when the speakers are 20 cm apart. The sound intensity decreases as the distance between the speakers is increased, reaching zero at a separation of 60 cm. a. What is the wavelength of the sound? b. If the distance between the speakers continuew to increase, at what separation will the sound intensity again be maximum. 5. The picture below shows two pulses approaching each other on a stretched string at time t = 0 3. Both pulses have a speed of 1.0 m/s. Using the empty graph axes below the picture, draw a picture of the string at t = 4 s