An iron ball, of mass 5 kg , and a ping-pong ball, of 5 g , are released from the top of a tower at the same time. Which of the following statements about their motion is/are correct? (Air resistance exists).
(1) Both balls have the same acceleration, 10ms^-2.
(2) The kinetic energy of the iron ball is larger.
(3) The iron ball reaches the ground first.
A. (1) only
B. (3) only
C. (1) and (2) only
D. (2) and (3) only
Physics MC
2007-04-19 2:57 am
回答 (3)
2007-04-19 3:35 am
✔ 最佳答案
答案為D,(1) 因ping-pong ball 的浮力與重量之比大過iron ball 的浮力與重量之比,換言之,討論iron ball 時,浮力幾乎可以忽略,而對ping-pong ball 而言,浮力不可忽略.iron ball 加速度大,故(1)錯.
(2) (題目應指明"落地時"的K.E.)因iron ball 的mass大,末速度也大,故落地時K.E.大.(2)對.
(3) 因iron ball的加速度大,故(3)對.
2007-04-19 3:01 am
An iron ball, of mass 5 kg , and a ping-pong ball, of 5 g , are released from the top of a tower at the same time. Which of the following statements about their motion is/are correct? (Air resistance exists).
(1) Both balls have the same acceleration, 10ms^-2.
(2) The kinetic energy of the iron ball is larger.
(3) The iron ball reaches the ground first.
Answer: A. (1) only.
(1) Both balls have the same acceleration, 10ms^-2.
(2) The kinetic energy of the iron ball is larger.
(3) The iron ball reaches the ground first.
Answer: A. (1) only.
參考: Myself.
2007-04-19 3:00 am
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