Passage Problems A spiral is an ice-skating position in which the skater glides on one foot with the other foot held above hip level. It's a required element in women's singles figure-skating competition and is related to the arabesque performed in ballet. Figure 5.40 shows Canadian skater Kaetlyn Osmond executing a spiral during her medal-winning perfor- mance at the 2018 Winter Olympics in Gangneung, South Korea. 77. From the photo, you can conclude that the skater is a. executing a turn to her left. b. executing a turn to her right. c. moving in a straight line out of the page. 78. The net force on the skater a. points to her left. b. points to her right. c. is zero. 79. If the skater were to execute the same maneuver but at higher speed, the tilt evident in the photo would be a. less. b. greater. c. unchanged. FIGURE 5.40 Passage Problems 77-80 80. The tilt angle 0 that the skater's body makes with the vertical is given ap- proximately by 0 = tan¯¹(0.5). From this you can conclude…

Frictionless surf

71. A 2.1-kg mass is connected to a spring with spring constant 72 k = 150 N/m and unstretched length 18 cm. The two are mounted on a frictionless air table, with the free end of the spring attached to a frictionless pivot. The mass is set into circular mo- tion at 1.4 m/s. Find the radius of its path. cor moving at 77 km/h negotiat CH —what's the minimum icient of frictio