Larry leaves home at 2:08 and runs at a constant speed to the lamppost. He reaches the lamppost at 2:15, immediately turns, and runs to the tree. Larry arrives at the tree at 2:29. What is Larry's average velocity during his trip from home to the lamppost, if the lamppost is 308.0 m west of home, and the tree is 688.0 m east of home?

Question

Larry leaves home at 2:08 and runs at a constant speed to the lamppost. He reaches the lamppost at 2:15, immediately turns, and runs to the tree. Larry arrives at the tree at 2:29. What is Larry's average velocity during his trip from home to the lamppost, if the lamppost is 308.0 m west of home, and the tree is 688.0 m east of home? 
 
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velocity is change of position (a vector) per time.

change of position: final position-initial 
= 688E+308W=380W

avgvelocity=380W/total time.

I got

avgvelocity = 380W/ total time
            = 380 / 21 seconds
            = 18.1 m/s

Why is my answer incorrect?

bobpursley · Answer

Rereading. The lamppost is 308m west of home. velocity=308/time

Vishnu · Answer

308/21 = 14.66 m/s I still get a wrong answer