高台跳雪运动员从赛道高处滑下，即将到达赛道底部时，运动员双脚使劲一蹬，顺势跃向高空．然后上身前倾，双臂后摆，向前滑翔，两边的雪松飞快地向后掠过．最终，滑雪板稳稳地接触地面．

请你结合上述情境，仿照示例写出高台跳雪运动中所包含的两个物理知识．

示例：运动员从赛道高处滑下﹣﹣重力势能转化为动能．

 Choose Your One-Day-Tours!

    Tour A - Bath &Stonehenge: including entrance fees to the ancient Roman bathrooms and Stonehenge -￡37 until 26 March and ￡39 thereafter.

     Visit the city with over 2,000 years of history and Bath Abbey, the Royal Crescent and the Costume Museum, Stonehenge is one of the world's most famous prehistoric monuments dating back over 5,000 years.

     Tour B - Oxford & Startford  including entrance fees to the University St Mary's Church Tower and Anne Hathaway's -￡32 until 12 March and ￡36 thereafter

     Oxford: Includes a guided tour of England's oldest university city and colleges. Look over the "city of dreaming spires(尖顶）"from St Mary’s Church Tower. Stratford: Includes a guided tour exploring much of the Shakespeare wonder.

     Tour C - Windsor Castle &Hampton Court including entrance fees to Hampton Court Palace -￡34 until 11 March and ￡37 thereafter.

Includes a guided tour of Windsor and Hampton Court, Henry VILL's favorite palace. Free time to visit Windsor Castle(entrance fees not included).With 500 years of history, Hampton Court was once the home of four Kings and one Queen. Now this former royal palace is open to the public as a major tourist attraction. Visit the palace and its various historic gardens, which include the famous maze(迷宫)where it is easy to get lost!

     Tour D -Cambridge including entrance fees to the Tower of Saint Mary the Great -￡33 until 18 March and ￡37 thereafter.

Includes a guided tour of Cambridge, the famous university town, and the gardens of the 18th century.

阅读下面的文言文，完成下小题。

    羊欣，字敬元，泰山南城人也。曾祖忱，晋徐州刺史。祖权，黄门郎。父不疑，桂阳太守。欣少靖默，无竞于人，美言笑，善容止。泛览经籍，尤长隶书。不疑初为乌程令，欣时年十二，时王献之为吴兴太守，甚知爱之。献之尝夏月入县，欣著新绢裙昼寝，献之书裙数幅而去。欣本工书，因此弥善。起家辅国参军，府解还家。隆安中，朝廷渐乱，欣优游私门，不复进仕。会稽王世子元显每使欣书常辞不奉命元显怒乃以为其后军府舍人。此职本用寒人，欣意貌恬然，不以高卑见色，论者称焉。欣尝诣领军将军谢混，混拂席改服，然后见之。时混族子灵运在坐，退告族兄瞻曰：“望蔡见羊欣，遂易衣改席。”欣由此益知名。

    桓玄辅政，领平西将军，以欣为平西参军，仍转主簿，参预机要。欣欲自疏，时漏密事，玄觉其此意，愈重之，迁以为楚台殿中郎。谓曰：“尚书政事之本，殿中礼乐所出。卿昔处股肱，方此为轻也。”欣拜职少日，称病自免，屏居里巷，十余年不出。

    义熙中，弟徽被遇于高祖，高祖谓咨议参军郑鲜之曰：“羊徽一时美器，世论犹在兄后，恨不识之。”即板欣补右将军刘籓司马，转长史，中军将军道怜谘议参军。出为新安太守。在郡四年，简惠著称。除临川王义庆辅国长史，庐陵王义真车骑谘议参军，并不就。太祖重之，以为新安太守，前后凡十三年，游玩山水，甚得适性。转在义兴，非其好也。顷之，又称病笃自免归。除中散大夫。

    素好黄老，常手自书章，有病不服药，饮符水而已。兼善医术，撰《药方》十卷。欣以不堪拜伏，辞不朝觐，高祖、太祖并恨不识之。自非寻省近亲，不妄行诣，行必由城外，未尝入六关。元嘉十九年，卒，时年七十三。子俊，早卒。（节选自《宋书•羊欣传》）