return an object in his original position

Audio and Graphics
#1

how can i make an object return in his original position with the “bounce”? 

this is the code that i wrote:

local physics = require( “physics” )

physics.start()

local bg=display.newImage(“background.jpg”)

local w,h=display.contentWidth, display.contentHeight

local ret=display.newRect(0,0,75,75)

local latSx=display.newRect(325,0,10,200)

transition.to(ret,{time=600,x=(w),})

physics.addBody(latSx,“static”,{bounce=1.0})

physics.addBody(ret,{bounce=1.0})