Question

What is the speed of an object that travels from `( -9,4,-6)` to `( -5,1,-2 )` over `3 s`?

Answer 1

The speed is 2.13 m/s.

Explanation:

The distance between two points in the space is given by
`d=sqrt((x_1-x_2)^2+(y_1-y_2)^2+(z_1-z_2)^2)`.
This is the Pitagora's theorem in three dimensions.
The speed is simply the space (in this case the distance) divided by the time.

`d=sqrt((-9+5)^2+(4-1)^2+(-6+2)^2)=sqrt((-4)^2+3^2+(-4)^2)=sqrt(41)\approx 6.4 m`
`v=6.4/3\approx 2.13` m/s