Posted by Melinda on .
Someone verify if this is correct, please!
1. Draw a distance versus time graph that corresponds to the walk described below.
Adam starts 8 m away from the motion sensor and walks in a straight line toward the sensor at a constant rate of 0.5 m/s for 3 s. He immediately begins walking away from the sensor at a constant rate of 0.25 m/s for 4s. He stops for 1s and then walks toward the sensor at a constant rate of 0.5 m/s for 2 s.
Image is here imgur dot com/aKwAy

2.
During what interval of time was the greatest distance travelled?
a) 0<t<5
b) 5<t<7
c) 7<t<10
d) cannot be determined
I don't which one is correct, 0<t<5 or 5<t<7
here is the image:
imgur dot com/vOojV
Thank yhou~

Math 
MathMate,
For (1), the xcoordinates are plotted correctly. You will need to review the ycoordinates, because they do not seem to correspond with the ones given in the question.
The starting point of 8 m is correct.
Walking towards the sensor makes a line with negative slope is correct also.
The rate is 0.5m/sec., so over 3 seconds, he would have been closer by 3*0.5=1.5m.
So at the end of 3 seconds, he would be at a distance of 81.5=6.5 m from the sensor.
Proceed this way for the rest of the question and see if you arrive at 6.5 m at the end of the 10 seconds.
(2) You'd need to interpret the graph where the yaxis represents speed given by m/s.
Interval, speed
05 3m/s
57 4m/s
710 1m/s
Since distance = speed * time, you can calculate the distance covered in each interval and the interval with the greatest distance travelled is the right answer. 
Math 
Melinda,
Got it! THank you~~~~~~~

Math :) 
MathMate,
Great! You're welcome!