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2 years ago

9

A motorboat travels 9 miles downstream (with the current) in 30 minutes. The return trip upstream (against the current) takes 90

minutes.
Which system of equations can be used to find x, the speed of the boat in miles per hour, and y, the speed of the current in miles per hour? Recall the formula d = rt.

9 = 0.5(x _ y)
9 = 1.5(x + y)

9 = 1.5(x _ y)
9 = 0.5(x + y)

0.5 = 9(x _ y)
1.5 = 9(x + y)

1.5 = 9(x _ y)
0.5 = 9(x + y)

2 answers:

Contact [7]2 years ago

7 0

9 = 1.5(x – y)

9 = 0.5(x + y)

Answer: B

Yanka [14]2 years ago

5 0

When moving with the current, the speeds of the boat and current will add up. The first situation can then be represented by:
9 = 0.5(x + y)
While opposing the current, the speeds will be subtracted. Forming:
9 = 1.5(x - y)
The second option contains this equation system, so it is correct.

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Substituting (5) in (6):

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The maximum acceleration $a_{max}$ is when the force is maximum $F_{max}$ , as well :

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