[填空题]
You are explaining we a,4g o.b4 lo+/zqgvgme :e3phy aab l;mi9v)ytg+oss 1b/d n+ p,stronauts feel weightless while orbiting in the space shuttle. Your friends respond that they thought grso/mat9nis bvpdl+,y g)1+b;avity was just a lot weaker up there. Convince them and yourself that it isn’t so by calculating the acceleration of gravity 250 km above the Earth’s surface in terms of g.
