Answer
a) $10m/s$
b) We can see that the winner A has started with high speed and with negative acceleration , so the speed gets decreased with time.
Winner B skied with has started with the constant speed, thus no acceleration.
Winner C has started with low speed and with positive acceleration , so the speed gets increased with time.
Work Step by Step
a) The average speed is given by $Speed_{avg.}=\dfrac{Distance}{Time}$
Thus, we have $Speed_{avg.}=\dfrac{Distance}{Time}=\dfrac{100}{10}=10 m/s$
b) We can see that the winner A has started with high speed and with negative acceleration , so the speed gets decreased with time.
Winner B skied with has started with the constant speed, thus no acceleration.
Winner C has started with less speed and with positive acceleration , so the speed gets increased with time.
