They are looking forward to an exciting vacation.
宇航员在某星球表面让一个小球以v0的速度做竖直上抛运动,经过时间t小球落回到抛出点,万有引力常量为G,若忽略星球自传.
用四舍五入法,按括号里的要求对下列各数取近似值: