john is rollerblading down a long, straight path. at time zero, there is a mailbox about 1 m in front of him. in the 5 s time period that follows, john's velocity is given by the velocity versus time graph in the figure. taking the mailbox to mark the zero location, with positions beyond the mailbox as positive, plot his position versus time in the given position versus time graph.

Ateacher attaches a ball to a meter long string and whirls it around in a horizontal circle at constant speed. the teacher explains that the string is what makes the ball go in a circle. why is the string necessary? a) the string is needed to apply a torque to the ball. b) the string is needed to push on the ball to get it up to speed. c) circle motion requires an inertia which is provided by the string. d) circle motion requires a force to give it a centripetal acceleratio