# What is the speed of an object that travels from ( -2,1,2)  to ( -3, 0,-6 )  over 3 s?

Dec 29, 2015

$1.41 \text{units""/s}$

#### Explanation:

To get the distance between 2 points in 3D space you effectively use Pythagoras in 2 D (x.y) and then apply that result to 3D (x,y,z).

Lets call $P = \left(- 2 , 1 , 2\right)$

and $Q = \left(- 3 , 0 , 6\right)$

Then $d \left(P , Q\right) = \stackrel{\rightarrow}{P Q}$

$= \sqrt{{\left(- 2 + 3\right)}^{2} + {\left(1 - 0\right)}^{2} + {\left(2 - 6\right)}^{2}}$

$= \sqrt{18}$

$= 4.24$

$\therefore v = \frac{4.24}{3} = 1.41 \text{units/s}$