Answer
(a) My average speed is 25.0 m/s. Equal time is spent at 20.0 m/s and 30.0 m/s.
(b) $Average$ $speed=25.0m/s$
Work Step by Step
$10.0 min = (10.0min)(\frac{60s}{1min})=600 s$
$Distance_{1}=(average speed_{1})(time elapsed_{1})=(20.0m/)(600s)=12000m$
$Distance_{2}=(average speed_{2})(time elapsed_{2})=(30.0m/)(600s)=18000m$
$Total$ $time$ $elapsed=600s+600s=1200s$
$Total$ $distance = 12000m+18000m=30000m$
$Average$ $speed=\frac{total distance}{total time elapsed}=\frac{3000m}{1200s}=25.0m/s$
