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A runner jogs a along a straight road (in the +x direction) for 30 min, travelling a distance of 6 km. She then turns around and walks back towards her starting point for 20 min, travelling 2 km during this time. State true/ false: a. The final displacement of the entire trip is 0.16 km min^(-1) . b. Her average speed for the entire is 0.16 km min^(-1). c. The average velocity for the entire trip is 0.4 km min^(-1). d. The runner's average velocity while jogging is 0.4 km min^(-1). e. Her average velocity while walking is 0.1 km min^(-1). |
Answer»  , `{:(Position""Time),(x_(0)=0""t_(0)=0), ("Jogging"""x_(1) =6 km""t_(1) =30 min),("Walking"""x_(2)=4 km""t_(2) =50 min):}` a. True,`Delta x=(x_(2)-x_(0))=3 km-0) =4 km` b. True , average =`(Total distance)/(Total time) =(8KM)/(50 mi n)` c. False, the average velocity for the entire trip is ` v_(av) =(Delta x)/(Delta t) =((x_(2)-x_(0)))/((t_(2)-t_(0)))=(4-0)/(50-0) =0.080 km min^(-2)` ltbrtgt d. False, while jogging `v_(av)=(Deltax)/(Deltat) =((x_(1)-x_(0)))/((t_(1)-t_(0))) =(6-0)/(30-0) =0.2000 km min^(-1)` e. True, while walking `v_(av)=(Delta x)/(Delta t) =((x_(2)-x_(1)))/((t_(2)-t_(1))) =((4 km -6 km))/((50 min-30 mi n))` `=(-2 km)/(20 mi n) =-0.100 km min^(-1) (walki ng)` The negative value indicates a velocity in the -`x` direction. A word of CAUTION: Please note that the runner`s average velocity for the entire trip is not SIMPLY the average of her jogging and walking velocities, because the times she spends in the these two different motions are not EQUAL. |
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