Question

Translate into an algebraic expression: If I travel d miles in h hrs downstream on a river with a current of c mph, what would my speed in still water have been?

Answer 1

Answer:

The speed is still water is $v = \frac{d}{h} - c$.

Step-by-step explanation:

Dimentionally speaking, speed is distance divided by time. Since, the person is travelling downstream, absolute speed is equal to the sum of current speed and speed of the person regarding current. Both components are constant. That is:

$c + v = \frac{d}{h}$

Where:

$c$ - Current speed, measured in miles per hour.

$v$ - Speed of the person regarding current, measured in miles per hour.

$d$ - Distance travelled downstream, measured in miles.

$h$ - Time spent on travelling, measured in hours.

Speed in still water occurs when current speed is zero. Then, such variable is obtained after subtracting current speed on both sides of the expression. Hence:

$v = \frac{d}{h} - c$

The speed is still water is $v = \frac{d}{h} - c$.