帮忙翻译两个关于机械的英文句子
aflat-facedfollowercannotcontactaconcavecamsurfaceinasinglepoint.therefore,suchconcavitiesarenotacceptableincamsforuswithflat-facedfollowers.thetranslationalmomentumofabodyisgivenbytheproductmvi.e.,byitsmassmtimesitvelocityvectorv.