Physics
2007-07-23 4:02 am
A toy gun mounted on a small trolley has a total mass of 0.2kg. The gun fires a 0.5g plastic bullet every second, ata speed of 6 m/s. If the trolley is initially at rest, what would be its speed after 10 s?
回答 (2)
2007-07-29 8:40 pm
✔ 最佳答案
設這題目中，每顆子彈的速度都是對地為6m/s。每顆子彈的質量都是 0.0005kg
每秒鐘射出一顆子彈，10s中共射出10粒子彈，所以10顆子彈共獲得
Δp = nmΔv
= 10 x 0.0005 x (6-0)
= 0.03 kg m / s
發射10顆子彈後，小車和槍的餘下質量是
m’= m – Δm = 0.2kg – 0.0005x10 = 0.195kg
依動量守恒，小車的速度變為
m’v = Δp
v = 0.03 / 0.195
= 0.154m/s
2007-07-23 4:22 am
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070722000051KK03544