Question 1209809: Mark is involved in a cross country run and starts down the path at his normal pace; he usually covers 12 m in 2.0 s. After tying his shoelace for 15 s, Frank discovers that he has just given Mark a large lead. Nonetheless, Frank is faster at 6.5 m/s. Determine:
How long does it take Frank to catch Mark? (180 s)
If the race is 3 km in length, who finishes first and by what distance? (Frank, 140 m)
Answer by ikleyn(52903)   (Show Source):
You can put this solution on YOUR website! .
Mark is involved in a cross country run and starts down the path at his normal pace;
he usually covers 12 m in 2.0 s.
After tying his shoelace for 15 s, Frank discovers that he has just given Mark a large lead.
Nonetheless, Frank is faster at 6.5 m/s. Determine:
(a) How long does it take Frank to catch Mark? (180 s)
(b) If the race is 3 km in length, who finishes first and by what distance? (Frank, 140 m)
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The solution for (a)
Mark' speed is 12/2 = 6 m/s; Frank' speed is 6.5 m/s.
Let "t" be the time for Frank to catch Mark.
Equate distances for Mark and for Frank
Mark Frank
6*(t+15) = 6.5*t.
Simplify and find t
6t + 90 = 6.5t
90 = 6.5t - 6t
90 = 0.5t
t = 90/0.5 = 180 seconds.
Frank will catch Mark in 180 seconds.
Solved.
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