同学们从生活中知道,密度比液体小的物体总是上浮到液面上.钢铁的密度比水大得多,用其制成的空心铁球却能浮在水面上,这是为什么呢?不少同学纳闷.其实判断物体的浮沉有两种办法.当物体浸没液体中时,①根据重力与浮力进行比较,如G< Students know from life that objects that are less dense than liquid always float to the surface, and that the density of steel is much greater than that of water, and hollow iron balls made of it float on the surface of the water. Why? Many students wonder .In fact, there are two ways to determine the object floating.When the object immersed in liquid, ① according to the comparison of gravity and buoyancy, such as G <