What is the speed of an object that travels from $( 7 , -4, 3 )$ to $( -2 , 4, 9 )$ over $4 s$ ?

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Answer 1 · 2016-04-28T21:06:29

$s=d/t=(13.45m)/(4s)=3.36$ $ms^-1$

First find the distance between the points, assuming distances are in metres:

$r=sqrt((x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2)$
$=sqrt(((-2)-7)^2+(4-(-4))^2+(9-3)^2)$
$=sqrt(-9^2+8^2+6^2)=sqrt(81+64+36)=sqrt181~~13.45$ $m$

Then speed is just distance divided by time:

$s=d/t=13.45/4=3.36$ $ms^-1$

What is the speed of an object that travels from ( 7 , -4, 3 ) ( 7 , -4, 3 ) to ( -2 , 4, 9 ) ( -2 , 4, 9 ) over 4 s4 s?