An object moves at due east at and still due east at

PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

An object moves at

4\,\text{m/s}

due east at

t=0\,\text{s}

and still

4\,\text{m/s}

due east at

t=1\,\text{s}

. By

t=2\,\text{s}

it is moving

4\,\text{m/s}

due south. During which one-second interval, if any, is the object accelerating? Justify your choice in one sentence.