Sally is concerned about the x-ray images her dentist plans to take of her teeth. she has read that x-rays can cause tissue effects, such as skin reddening and hair loss. which statement would best inform sally of the level of risk? a) the dentist uses x-ray fluoroscopy, which can take enough time to cause those problems. b) the dentist uses x-ray radiography, which takes too short a time to cause those problems. c) the dentist uses x-ray fluoroscopy, which takes too short a time to cause those problems. d) the dentist uses x-ray radiography, which can take enough time to cause those problems.

Review multiple-concept example 7 in this chapter as an aid in solving this problem. in a fast-pitch softball game the pitcher is impressive to watch, as she delivers a pitch by rapidly whirling her arm around so that the ball in her hand moves in a circle. in one instance, the radius of the circle is 0.626 m. at one point on this circle, the ball has an angular acceleration of 66.1 rad/s2 and an angular speed of 12.6 rad/s. (a) find the magnitude of the total acceleration (centripetal plus tangential) of the ball. (b) determine the angle of the total acceleration relative to the radial direction.