Question

Open with Physics 1214, General Physics -I, Fall 2019 Recitation Problems 9- Chapters 9, 10, 12, 11 PROBLEMS: SHOW ALL WORK, not just the answers 1. From a stationary position at 0-0, a bicycle wheel accelerates with a constant angular acceleration of a = 10.0 s a) What is its angular velocity o after 5 s? b) What is its angular position 0 at that time? 2. An iceskater is turning at a PERIOD of (1/3) second with his arms outstretched. a) What is his ANGULAR VELOCITY o? b) If he pulls his arms towards his body to reduce his MOMENT OF INTERTIA by /, what is his ANGULAR VELOCITY o? c) How much does his ROTATIONAL KINETIC ENERGY change? That is, if the initial Kinetic Energy is (KE)initial, What is the final KE? d) Where did that ENERGY come from, or go to? 3. A sound wave has wavelength 1 2.00 m and frequency f 173 s1, how fast is it moving through the air? 4. The person playing first violin is playing an A note at 440 s1. The person who is playing second violin had a difficult day yesterday and is mistakenly playing a B note at 493 s1 Describe their combined sound. 5. An unbelievably LOUD car alarm at 4:12 AM at the intersection of Jewel Avenue and 150th Street sends out a pure tone at 400 s1. The speed of sound is 343 m/s. What frequency is heard from: a) a car racing TOWARD it at 50 m/s (112 mph) b) a car racing AWAY from it at 50 m/s (112 mph) 6. In the Hitchhikers Guide to the Galaxy by Douglas Adams, the rock band Disaster Area is the loudest band in the Galaxy. They set up two speakers (dots) spaced 0.600 m apart on a wall that opens out to the east. When they play their signature sound at 1,000 Hz which has a wavelength of 0.300 m, what are ALL the directions, far from their stage, along which their sound is the loudest? (HINT: constructive interference.) Page 12

Answer 1

Am initial position, & Orad. initial angular velocity, Wizo constant angular accih, a = 1000 rad/5. after t=5sec, (as angular velocity, w z W; txt=of 60.0x5)=50rad/s b) angular position, 0 = 8+W;t+{&t=0+0x5) + 5x10X(5) = 125 rad. Aus