Physics

Problem

A skateboarder starts from rest at

t=0

and moves east. The skateboarder accelerates uniformly, reaching a speed of

6\,\text{m/s}

t=2\,\text{s}

. Without stopping, the skateboarder then slows down uniformly to rest at

t=5\,\text{s}

. Which of the following qualitative descriptions best matches the skateboarder’s velocity–time graph for the entire

0

–

5\,\text{s}

interval? a) A horizontal line at

6\,\text{m/s}

from

t=0

2\,\text{s}

, followed by a straight line sloping down to

0

t=5\,\text{s}

b) A smooth curved (parabolic) rise from

0

6\,\text{m/s}

t=2\,\text{s}

, then a similar curved return to

0

t=5\,\text{s}

c) A straight line rising from

0

6\,\text{m/s}

between

t=0

and

2\,\text{s}

, followed by a straight line sloping back down to

0

t=5\,\text{s}

d) A straight line rising from

0

6\,\text{m/s}

between

t=0

and

2\,\text{s}

, followed by a horizontal line at

6\,\text{m/s}

until

t=5\,\text{s}