What is the speed of an object that travels from ( -9,0,1) to ( -1,4,3 ) over 2 s?

1 Answer
Apr 19, 2016

speed: sqrt(21) "units"/"sec" ~~4.58 "units"/"sec"

Explanation:

Distance between (-9,0,1) and (-1,4,3)
is
color(white)("XXX")d=sqrt((-1-(-9))^2+(4-0)^2+(3-1)^2)
color(white)("XXXx")=sqrt(8^2+4^2+2^2)
color(white)("XXXx")=sqrt(64+16+4)
color(white)("XXXx")=sqrt(84)
color(white)("XXXx")=2sqrt(21) (units)

Assuming a constant speed, s
color(white)("XXX")"speed" = "distance"/"time"
So
color(white)("XXX")s=(2sqrt(21) " units")/(2 " sec")

color(white)("XXX")=sqrt(21) "units"/"sec"

color(white)("XXX")sqrt(21)~~4.58 (using a calculator)