Question

A flea walking along a ruler moves from the 45 cm mark to the 27 cm mark. It does this in 3 seconds. What is the speed? What is the velocity?

(Define increasing numbers to be the positive direction and decreasing numbers to be the negative direction.)

Answer 1

Speed= 6cm/s and velocity= 6cm/s in the negative direction

Step-by-step explanation:

the change in position is from 45cm to 27 cm (moving towards the negative x direction)

`\Delta x = 45 cm - 27 cm = 18 cm`

And the change in time:

`\Delta t= 3 s`

Now we must define the difference between speed and velocity:

Speed is a scalar quantity, which means that it is a number. Velocity ​​is also a number but you must also indicate the direction of the movement.

Thus, the speed is:

`speed= \Delta x/ \Delta t = 18cm/3s=6cm/s`

An the velocity is:

6cm/s in the negative direction