Problem 2 (13 points) Ground squirrels design their burrows so that one end is on the ground level, while the other end is elevated by several feet. Wind causes air to flow near the elevated entrance, while the air is at rest near the ground (due to friction}. This will ensure a Steady airow through the tunnel and natural air conditioning. wind (a) On a windy day the air velocity above the right (elevated) entrance is 7.5 m / s. The elevated entrance is 50 cm above the ground level entrance. If the air pressure without wind is 1.0 atm, what is the absolute pressure at the right entrance and the pressure difference between the left and right entrance? The density of air is 1.2 kg/mg. (9 points) (a) Indicate the direction of air ow inside the tunnel in the gure above and state how the pressure difference from (a)1 and the tunnel length and cross section affect the ow-rate. {4 points) Problem 3 (16 points) One end of a horizontal string of linear mass density 1.5-10 8 kg/m is attached to a small-amplitude vertical oscillator of fixed frequency f=200 Ha. The string passes over a pulley a distance of L=0.80 m away from the oscillator end. A mass m is hung from this end as shown to provide tension. m (a) What mass m is required to produce a standing wave with three nodes? (10 points) (b) Find w, k, and > of the sound wave emitted by this vibrating string (4 points) Please see last page! (c) Assume now that the mass is fixed at 250 g. How many different standing wave patterns may be achieved with this setup by varying the distance L between oscillator end and pulley between 30 cm and 100 cm? (2 points