HELP I DON'T KNOW HOW TO DO THIS!!!

The race is 200 meters long.  So we want to look at the graph and see which runner was the first to cover 200 meters.

==> All 3 runners were at the starting line (0 m) when the clock said 0 sec. So nobody jumped out ahead before time=0, and it was a fair start.

==> Runners B and C both arrived at 200 m when the clock said 25 sec.

==> Runner-A arrived at 200 m when the clock said 20 sec.  So he was there first, and won the race.

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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