题目

Many teenagers(青少年) feel that the most important people in their lives are their friends．They believe that their family members don’t know them as well as their friends do．In large families, it is quite often for brothers and sisters to fight with each other and then they can only go to their friends for some ideas． It is very important for teenagers to have one good friend or a group of friends．Even when they are not with their friends, they usually spend a lot of time talking among themselves on the phone．This communication is very important in children’s growing up, beca（2012?宝坻区二模）美术课上同学们用橡皮泥捏动物模型时，想知道橡皮泥的密度有多大．课后，他们取了一块质量为10-15g的橡皮泥，采用了两种实验方案，来测量橡皮泥的密度．方案一：所用器材为弹簧测力计（如图）、水（密度用ρ水表示）和细线，实验步骤如下：a．将橡皮泥用线系好，用测力计测出橡皮泥的重力G；b．将测力计吊着的橡皮泥浸没水中，读出这时测力计的示数为F．（1）则可知橡皮泥密度的表达式为：V3-V1V2-V1ρ水V3-V1V2-V1ρ水（2）请你评价：在该方案中能不能测出橡皮泥的密度？为什么？方案二：所用器材为量筒和水．（3）请写出此方案的实验步骤（画图说明也可以）．