A7.0−kg object is at rest on a perfectly frictionless surface when it is struck head-on by a 3.5−kg object moving at 13 m/s. if the collision is perfectly elastic, what is the speed of the 7.0−kg object after the collision? [hint: you will need two equations.]

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.