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大学物理英语习题
University Physics AI
No. 1 Rectilinear Motion
Class Number Name
I．Choose the Correct Answer
1. An object is moving along the x axis with position as a function of time given by x = x(t) . Point
O is at x = 0 . The object is definitely moving toward O when ( C )
(A) 0Solution: If the object is moving toward O, the velocity and the position vector of the object have
different direction. That is 0xv x x , so the answer is C.
2．An object starts from rest at x=0 when t=0. The object moves in the x direction with positive
velocity after t=0. The instantaneous velocity and average velocity are related by ( D )
(A) dx / dt ﹤ x / t . (B) dx / dt = x / t . (C) dx / dt ﹥ x / t .
(D) dx / dt can be larger than , smaller than, or equal to x/t.
Solution: The instantaneous velocity and average velocity are both positive , the
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University Physics AI
No. 12 The Second Law of Thermodynamics
Class Number Name
I．Choose the Correct Answer
1. A real engine has an efficiency of 33%. The engine has a work output of 24J per cycle. How
much heat energy is extracted from the high- temperature reservoir per cycle? ( D )
(A) 8J (B) 16J (C) 48J (D) 72J
(E) The question can be answered only of the engine is a Carnot engine.
Solution:
Using the definition of the efficiencyQ W H .
2. A real engine has an efficiency of 33%. The engine has a work output of 24J per cycle. For this
engine TL=27°C. What can be concluded about TH? （ C ）
(A) TH =450°C. (B) TH =177°C (C) TH ﹥177°C (D) TH ﹤177°C. (E) 177°C ﹤TH ﹤
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