题目

Last year，I was assigned to work at an office near my mother's house.______，I stayed with her for a month. During that time，I helped her out with the housework and contributed to the______．After a week，I started______the groceries were running out pretty quickly. ______，I began observing my mother's daily routine for two weeks. To my______，I found she would pack a paper bag full of canned goods and______every morning at about nine. She took the food to the slums(贫民窟)and distributed it to street______．I asked around and______my mum was popular in the area. The kids looked 如图所示，是探究“动能的大小与什么因素有关”的实验装置，实验中让同一钢球从斜面上不同的高度由静止滚下，碰到同一木块上．请问：实验的目的是探究钢球动能的大小与______的关系；实验时，它是通过观察______，从而判断钢球动能的大小．