# Speed related to Average Velocity

1. Jan 31, 2012

### suessthezeus

1. The problem statement, all variables and given/known data

A car travels along a straight line at a constant speed of 47.0 mi/h for a distance d and then another distance d in the same direction at another constant speed. The average velocity for the entire trip is 33.5 mi/h.

2. Relevant equations

3. The attempt at a solution

I have been trying to think of it in these terms

(54 + Q) = 33.5

I know this isn't right....can I get some direction

Thanks!!!

2. Jan 31, 2012

### Aquariouse

Velocity is a vector, meaning that it has a size and direction, speed is a scalar meaning that it only has a size.

Assuming relative values , distance d is equal to distance d, your set up could be:
(47MPH Forward + (X)MPH Forward)/2d = 33.5 Forward

Let d be any real number, in this case the simplest number, one. you would then have:
(47MPH Forward +(X)MPH Forward)/2 = 33.5 Forward
(47MPH Forward +(X)MPH Forward) = 67

Remember if it ask for a vector as a answer you MUST provide direction.

SPOILER: Attempted Soution-
X MPH Forward = 20

3. Jan 31, 2012

Where does (54+Q) come from? This probably belongs in the relevant equations section.
speed is a scalar quantity, average velocity is a vector
also
this isn't asking a clear question, despite it's presence in the problem statement

4. Jan 31, 2012

### Aquariouse

I think he is solving for the second "constant speed"

5. Jan 31, 2012