Question

A person starts at a position of 29 meters and finishes at a position of 2 meters. The trip takes 4.5 seconds. What is the person's average velocity? What is the person’s average speed?

Answer 1

Speed= 6 m/s

Velocity=-6 m/s or 6 m/s to the left

Step-by-step explanation:

Speed is a scalar quantity and is always positive, while velocity is a vector; hence it must have a direction and a module (the speed).

In other words, the speed is the module of te velocity vector.

In this sense, average velocity
`V` and average speed
`S` are defined as:

`V=(\Delta X)/(\Delta t)` (1)

Where
`\Delta X` is the object's variation in position and
`\Delta t` is the time

`S=(d)/(t)` (2)

Where
`d` is the distance traveled and
`t` is the time of travel

Now, according to the given information, the person started at an initial position
`X_(o)=29 m` and finished at a final position
`X_(f)=2 m`.

This means the variation in position
`\Delta X` (assuming the person is moving along the X-axis or horizontally) is:

`\Delta X=X_(f) - X_(o)= 2 m - 29 m`

`\Delta X=-27 m`

And
`\Delta t=4.5 s`

Then, the average velocity is:

`V=(-27 m)/(4.5 s)` (3)

`V=- 6 m/s` (4) As we can see, the negative sign indicates the direction, which is to the left (or to the West if the person is traveling along a West-East highway, for example)

On the other hand, if we calculate the distance traveled by this person we have to take the difference between the two points:

`d=29 m - 2 m = 27 m`

As we know the time of travel
`t` is also
`4. 5 s`, the average speed is:

`S=(27 m)/(4.5 s)` (4)

`S=6 m/s` (5)