8.) A candle, a converging lens and a white screen are placed in a line with the lens between the candle and the screen. A distance of 72 cm separates the candle and screen. As the lens is moved to all points between the candle and the screen, only one focused image of the candle can be made on the screen. What is the focal length of the converging lens?

(A) 12 cm
(B) 18 cm
(C) 24 cm
(D) 36 cm
(E) It cannot be determined without knowing the location of the lens when the focused image is produced.

35.) In a mixture of hydrogen, oxygen, and nitrogen gases at room temperature, the molecules having the greatest average speed are those of
(A) Hydrogen
(B) Oxygen
(C) Nitrogen
(D) All have the same speed
(E) It depends upon the composition of the mixture

44.) Consider a traveling wave on a string of length L, mass M, and tension T. A standing wave is set up. Which of the following is true?

(A) The wave velocity depends on M, L, T. 
(B) The wavelength of the wave is proportional to the frequency.
(C) The velocity of a given particle in the string is equal to the wave velocity.
(D) The wavelength is proportional to T.
(E) The frequency depends upon L.

49.) A lump of clay whose rest mass is 4.0 kg is traveling at three-fifths of the speed of light when it collides head-on with an identical lump going in the opposite direction at the same speed. If the two lumps stick together and no energy is radiated away, what is the mass of the composite lump?

(A) 4.0 kg (B) 6.4 kg (C) 8.0 kg (D) 10.0 kg (E) 13.3 kg

物理碗竞赛，众人眼中香饽饽,物理碗竞赛有多火爆？

物理碗竞赛备考建议

1）这就需要学生平时学习中完全吃透知识点，建立完整的知识体系。在做题时能够立马反应并及时解答。

2）其次在备战物理碗的时候要提前熟悉考试题型和风格，在考场上做题时才会快速进入状态，不会因为陌生感而惊慌失措，速度变慢。

3）最后就是要掌握高效的答题策略及拥有随机应变的能力。考场答题如有神助攻的状态是需要平时在专业老师的指导下去摸索和学习掌握的。

★ 个人奖

● 全球个人奖：全球排名前 100 位

● 全国金奖：中国排名前10%

● 全国银奖：中国排名前20%

● 全国铜奖：中国排名前35%

● 物理优秀奖：中国各赛区排名（除全国奖项外）前15%

★ 团队奖

● 全球获胜团队奖-全球排名前 50 位
● 全国获胜团队奖-全国前 10 名 (Division1、Division2)
● 区域获胜团队奖-区域前 10 名 (Division1、Division2)

*取本校个人成绩前 5 名加总为团体总分；若不足 5 人，则所有选手得分加总为团体分。

犀牛物理课程

犀牛金牌导师带队