Question

What is the speed of an object that travels from `( 8 , 4, 1 )` to `( 6 , 0, ,2 )` over `2 s`?

Answer 1

`v=sqrt 6" ""unit"/s`

Explanation:

`P_1(8,4,1) " "P_2(6,0,2)`
`P_"1x"=8" "P_"2x"=6" "Delta P_x=6-8=-2`
`P_"1y"=4" "P_"2y"=0" "Delta P_y=0-4=-4`
`P_"1z"=1" "P_"2z"=2" "Delta P_ z=2-1=2`
`" distance between the point of " P_1" and " P_2" is:"`
`Delta x=sqrt((Delta P_x)^2+(Delta P_y)^2+(Delta P_z)^2)`

`Delta x=sqrt((-2)^2+(-4)^2+2^2)=sqrt (4+16+4)=sqrt24`

`v=(Delta x)/t`

`v=sqrt 24/2`
`v=sqrt (4*6)/2`
`v=(cancel(2)*sqrt6)/cancel(2)`

`v=sqrt 6" ""unit"/s`