N
nsa.36


2 vong tron day dan dat cach nhau 1 khoang rat nho . vong day dan duoi co dinh , vong tren noi vs 1 dau don can . khi cho 2 dong dien cuong do bang nhau vao 2 vong day thi chung hut nhau . dat them 1 qua can khoi luong 0,1 g vao dia can ben kia thi can tro lai thang bang va luc do 2 vong cach nhau 2mm . xac dinh cuong do dong dien trong moi vong day . cho biet ban kinh moi vong day 5 cm.lay g = 10 m\s^2.
