Q1. A vaulter holds a 31.67-N pole in equilibrium by exerting an upward force U with her leading hand and a downward force D with her trailing hand. Point C is the center of gravity of the pole, a=0.750 m, b=1.63 m, c=2.03 m. What are the magnitudes of U?
Q2. A friend of yours is loudly singing a single note at 411 Hz while racing toward you at 25.5 m/s on a day when the speed of sound is 341 m/s.
1) what frequency do you hear?
2) What frequency does the friend hear if you suddenly start singing at 411 Hz?