Q1. A 2.20 sound wave travels through a pregnant woman's abdomen and is reflected from the fetal heart wall of her unborn baby. The heart wall is moving toward sound receiver as heart beats. The reflected sound is after that mixed with the transmitted sound, and 70 beats per second are detected. The speed of sound in body tissue is 1450.

Q2. The system of small objects shown is rotating at the angular speed of 4.0 rev/s. The objects are connected by light, flexible spokes that can be lengthened or shortened. What is the new angular speed if spokes are shortened to 0.15 m? (An effect similar to that illustrated in this problem occurred in the early stages of formation of our Galaxy. As the massive cloud of dust and gas that was source of the stars and planets contracted, an originally small rotation increased with time.)