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物理 高中

請問第二張照片紅線那邊 為什麼時間是用兩次撞擊的時間差算 不是應該撞擊瞬間的時間(碰到A面的時間)

45 (30 為 泡草 J 400 速 間沒 在一 總能 有位 可視 9 日世 況 T XCX PM 時 -V = 174 高中學習講義 選修物理 II 學習概念2 碰撞與氣體壓力的微觀論點推導(配合課本p.206) 1. 密閉容器內的氣體壓力: (1) 條件:氣體是由數目極龐大的分子所組成。(若分子數目太少時,分子行為可能偏離 平均值) 相等。 且分子的運動是「隨機」的,任一時段內向各方向運動的平均分子數目均 (2) 壓力來源: ⓊP:氣體分子的重量所造成。P:氣體分子不斷撞擊器壁所造成。 2 由於碰撞力遠大於分子重量故 P, > P,所以 P, 可忽略不計。 2. 平均壓力理論推導: (1) 說明:設邊長L、體積V(=L)的正立方體密閉容器內,有N 個相同的氣體分子,每個分子的質量均為m,如右圖。 (2)推導過程: 設將氣體分子逐一編號,其中編號第i個的氣體分子以 ^ v=vxi + urj + v.k的速度,入射 A, 面,如圖(一)因分子與器壁的碰撞為完全 彈性碰撞,則該分子與 A, 面碰撞後, 的速度分量 vi因與 4. 面垂直,故在碰撞 後變成 - va。而在y與z軸的速度分量 與vÊ不變,如圖(二)所示。 -Ux- U₁ A₂ Ax Uy U2OUx x ▲圖(一):第i顆氣體分子以速度朝4. ▲圖(二):分子撞擊器壁,其速度變化的情形。 面入射。 ② 則該分子的動量變化為Apx 2mus,即此分子在此次碰撞後,受到 4 面的衝量 == 為: J=Ap=-2musi (3) 當分子從 4. 面反彈後,有可能撞擊其他器壁面,因彈性碰撞,故其平行於x軸的速 度分量 vi速率不變,因此來回一次撞擊 4. 面,所經歷路程為 2L,共歷時 A t = 2L 。 Vix 故此第i個分子,施於面的平均力為: 015 Uz

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物理 高中

21題 教教我QAQ

Section 11.3 Angular Momentum J-s behind rmv a he ur 265 = ? a ter 30. Example 11.1: A 58.1 Iw COMP string and whirled at 18. Express the units of angular momentum (a) using only the funda- momentum of magr mental units kilogram, meter, and second; (b) in a form involving the circular path. Fir newtons; (c) in a form involving joules. marw horizontal and (b) the 19. Use data from Appendix E to make an order-of-magnitude esti- 31. Example 11.2. A stai mate for the angular momentum of our Solar System about the Max 27 the end of its lifetime galactic center. mu = 17.293 of radius 4.96 X 10' 20. A gymnast of rotational inertia 63 kg•m? is tumbling head over heels dwarf of radius 4.21 with angular momentum 460 kg•m?/s. What's her angular speed? 17.99 acted on the core, fine A 660-g hoop 95 cm in diameter is rotating at 170 rpm about its 32. Example 11.2: Astro 22. A 1.3-th-diameter golf ball has mass 45 g and is spinning at central axis. What's its angular momentum? L: 1W=0-66*(0-95) x 140x277.10 km and determin core that collapsed to 3000 rpm. Treating the golf ball as a uniform solid sphere, what's ing with a period of 4 its angular momentum? 18-3 33. Example 11.2. The s 10-598 rpm With her arms outstre Section 11.4 Conservation of Angular Momentum tational inertia is 3.5 23. A potter's wheel with rotational inertia 6.20 kg•m? is spinning (Fig. 11.6b), her rot freely at 20.0 rpm. The potter drops a 2.50-kg lump of clay onto her final spin rate? L = 6 2 x 2-1 = 12-99~13 - 2x2 22 13= 60.48)" x 2.5 W W = 2 . X z W = 20x2T 60 ²2.1 ~ 1 12.574

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物理 高中

第21題 到底要怎麼寫ಥ_ಥ

Section 11.3 Angular Momentum J-s behind rmv a he ur 265 = ? a ter 30. Example 11.1: A 58.1 Iw COMP string and whirled at 18. Express the units of angular momentum (a) using only the funda- momentum of magr mental units kilogram, meter, and second; (b) in a form involving the circular path. Fir newtons; (c) in a form involving joules. marw horizontal and (b) the 19. Use data from Appendix E to make an order-of-magnitude esti- 31. Example 11.2. A stai mate for the angular momentum of our Solar System about the Max 27 the end of its lifetime galactic center. mu = 17.293 of radius 4.96 X 10' 20. A gymnast of rotational inertia 63 kg•m? is tumbling head over heels dwarf of radius 4.21 with angular momentum 460 kg•m?/s. What's her angular speed? 17.99 acted on the core, fine A 660-g hoop 95 cm in diameter is rotating at 170 rpm about its 32. Example 11.2: Astro 22. A 1.3-th-diameter golf ball has mass 45 g and is spinning at central axis. What's its angular momentum? L: 1W=0-66*(0-95) x 140x277.10 km and determin core that collapsed to 3000 rpm. Treating the golf ball as a uniform solid sphere, what's ing with a period of 4 its angular momentum? 18-3 33. Example 11.2. The s 10-598 rpm With her arms outstre Section 11.4 Conservation of Angular Momentum tational inertia is 3.5 23. A potter's wheel with rotational inertia 6.20 kg•m? is spinning (Fig. 11.6b), her rot freely at 20.0 rpm. The potter drops a 2.50-kg lump of clay onto her final spin rate? L = 6 2 x 2-1 = 12-99~13 - 2x2 22 13= 60.48)" x 2.5 W W = 2 . X z W = 20x2T 60 ²2.1 ~ 1 12.574

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