Abox rests on top of a flat bed truck. the box has a mass of m = 18 kg. the coefficient of static friction between the box and truck is î¼s = 0.86 and the coefficient of kinetic friction between the box and truck is î¼k = 0.69. 1) the truck accelerates from rest to vf = 16 m/s in t = 16 s (which is slow enough that the box will not slide). what is the acceleration of the box?

An athlete swings a ball, connected to the end of a chain, in a horizontal circle. the athlete is able to rotate the ball at the rate of 8.13 rev/s when the length of the chain is 0.600 m. when he increases the length to 0.900 m, he is able to rotate the ball only 6.04 rev/s. (a) which rate of rotation gives the greater speed for the ball? 6.04 rev/s 8.13 rev/s (b) what is the centripetal acceleration of the ball at 8.13 rev/s? m/s2 (c) what is the centripetal acceleration at 6.04 rev/s? m/s2