你应该去中考物理吧问这个问题http://tieba.baidu.com/f?ct=&tn=&rn=&pn=&lm=&cm=0&kw=%D6%D0%BF%BC%CE%EF%C0%ED&rs2=0&sc=&un=&rs1=&rs5=&sn=&rs6=&myselectvalue=0&word=%D6%D0%BF%BC%CE%EF%C0%ED&tb=on
