Physics

Problem

Four motions, each lasting exactly

2.0\,\text{s}

, are described below. I. A cart speeds up from

0

8.0\,\text{m}\!\cdot\!\text{s}^{-1}

in a straight line. II. A gondola slows from

10\,\text{m}\!\cdot\!\text{s}^{-1}

4\,\text{m}\!\cdot\!\text{s}^{-1}

in a straight line. III. A car travels at a constant

6.0\,\text{m}\!\cdot\!\text{s}^{-1}

while turning such that its direction changes by

90^{\circ}

. IV. A seat moves at a constant

12\,\text{m}\!\cdot\!\text{s}^{-1}

in uniform circular motion, completing half a revolution (

180^{\circ}

). Rank the motions by the magnitude of their average acceleration during the

2.0\,\text{s}

interval, from greatest to least. a) I > II > III > IV b) IV > I > III > II c) IV > III > I > II d) IV > III > II > I