Better Students Ask More Questions.
This is a physics question.Runner A is initially 6 km west of a flagpole and running at...
This is a physics question.
Runner A is initially 6 km west of a flagpole and running at a constant velocity of 9.0 km/h due east. Runner B is initially 5 km east of the flagpole and is running west at a constant velocity of 8 km/h. What will be the position of the 2 runners from the flagpole when their paths cross.
Please use GUESS method and explain.
1 Answer | add yours
High School Teacher
Best answer as selected by question asker.
The GUESS method stands for givens, unknowns, equation, substitution, and solution.
In your problem:
G - givens are: initial position of each runner in relation to a reference point (flag pole) - for A this is 6 km and for B this is 5 km (this means they are 11 km apart); and the velocity of each runner. V(A) = 9 km/hr and V(B) = 8 km/hr.
U - unknown is where, in relation to the flagpole, will the two runner meet.
"E - equation. let X = distance that runner A has gone when they meet. then 11-X = distance runner B has gone. Using the formula time = distance/velocity; for runner A time = X/V(A) and for runner B time = (11-X)/V(B). Since times are equal for the two runners, the final equation is:
X/V(A) = (11-X)/V(B)
S - substitution
X/9 km/hr = (11 - X)/8 km/hr
S - Solve.
X = 5.82 km
This means that runner A has moved 5.82 km east from his starting point of 6 km. 6 - 5.82 means he is 0.18 km west of the flagpole.
For runner B he has moved 11-5.82 km west from his starting point. 11-5.82 = 5.18 km west. Since he started 5 km east, he is now 0.18 km west of the flagpole also.
Posted by ndnordic on August 30, 2011 at 10:50 PM (Answer #1)
Join to answer this question
Join a community of thousands of dedicated teachers and students.