煞車怎麼運作？我們使出所有招術，用在這一集「風火輪實驗室：摩擦力」！科學主題：摩擦力與煞車。#HotWheelsWatch the latest Hot Wheels videos: http://bit.ly/HW_MostRecentWATCH ALL OF THE HOT WHEELS SERIES:???? ...