▁of ▁an ▁object ▁may ▁be ▁assumed ▁to ▁be ▁concentr ated ▁to ▁visual ise ▁its ▁motion . ▁In ▁other ▁words , ▁the ▁center ▁of ▁mass ▁is ▁the ▁particle ▁equivalent ▁of ▁a ▁given ▁object ▁for ▁application ▁of ▁Newton ' s ▁laws ▁of ▁motion . ▁ ▁In ▁the ▁case ▁of ▁a ▁single ▁rig id ▁body , ▁the ▁center ▁of ▁mass ▁is ▁fixed ▁in ▁relation ▁to ▁the ▁body , ▁and ▁if ▁the ▁body ▁has ▁uniform ▁density , ▁it ▁will ▁be ▁located ▁at ▁the ▁cent roid . ▁ ▁The ▁center ▁of ▁mass ▁may ▁be ▁located ▁outside ▁the ▁physical ▁body , ▁as ▁is ▁sometimes ▁the ▁case ▁for ▁h ollow ▁or ▁open - sh aped ▁objects , ▁such ▁as ▁a ▁horses ho e . ▁ ▁In ▁the ▁case ▁of ▁a ▁distribution ▁of ▁separate ▁bodies , ▁such ▁as ▁the ▁plan ets ▁of ▁the ▁Sol ar ▁System , ▁the ▁center ▁of ▁mass ▁may ▁not ▁correspond ▁to ▁the ▁position ▁of ▁any ▁individual ▁member ▁of ▁the ▁system . ▁ ▁The ▁center ▁of ▁mass ▁is ▁a ▁useful ▁reference ▁point ▁for ▁calculations ▁in ▁mechan ics ▁that ▁involve ▁masses ▁distributed ▁in ▁space , ▁such ▁as ▁the ▁linear ▁and ▁angular ▁momentum ▁of ▁planet ary ▁bodies ▁and ▁rig id ▁body ▁dynamics . ▁In ▁orb ital ▁mechan ics , ▁the ▁equations ▁of ▁motion ▁of ▁plan ets ▁are ▁form ulated ▁as ▁point ▁masses ▁located ▁at ▁the ▁cent ers ▁of ▁mass . ▁ ▁The ▁center ▁of ▁mass ▁frame ▁is ▁an ▁in ert ial ▁frame ▁in ▁which ▁the ▁center ▁of ▁mass ▁of ▁a ▁system ▁is ▁at ▁rest ▁with ▁respect ▁to ▁the ▁origin ▁of