2. 2、 What mechanism can cause the entropy of a control mass to decrease?
(A) Work done on the system (B) Transfer heat to the system
(C) Transfer heat from the system (D) Irreversible process
3.3、 Using the parallel-axis theorem, determine the product of inertia of the area shown with
respect to the centroidal x and y axes ( Ixy)？ (A)138.24×103 mm4 (B) 69.12×106 mm4 (C) 138.24×106 mm4 (D) 69.12×103 mm4。
4. 4、 如圖 4 之懸臂樑結構，則在 C 點處所受之剪力為何? (A)1080 N, (B)980 N, (C)540 N, (D) 640 N。
5.5、 Which of the following failure theories is the most conservative?
(A) Maximum normal stress theory (B) Maximum shear stress theory
(C) Maximum distortion energy theory (D) Maximum normal strain theory
9.9、 The coefficient of static friction between the cord and the fixed shaft as shown is 0.2. What is
the minimum force P required to prevent the 2 kg from falling? (A) 2.98 N (B) 3.92 N (C) 19.6 N (D) 129 N
10.10、 In Figure 10, a horizontal force of 500 N acts on a block of weight 1.5 kN placed on an
inclined plane. The coefficients of friction between the block and the plane are
0.20 μk =
. What is the actual frictional force? (A) 200N (B) 500 N (C) 300 N (D) 450 N。
12.12、 A bar made of A-36 steel has the dimensions shown in Figure 12. An axial force P= 80kN is
applied to the bar, the young’s modulus for A-36 steel is E=200 GPa and the bar material
behaves elastically, which of the following is correct? (A) the axial elongation is 100 μm, (B) the axial elongation is 120 μm,
(C) change of the wide dimension is 3.67 μm, (D) change of the height dimension is 2.56 μm.
13.13、 水平桌面上有一油膜 (其黏性係數為 0.40 N-s/m2
)，油膜上有一平板以 5 m/s 之速度水
平移動。若油膜內之剪應力為 1 kPa，則油膜厚度為何？
(A) 0.2 mm (B) 1.6 mm (C) 2.0 mm (D) 3.5 mm。
32.32、 For the following physical situation, what’s the possible process in a P-V diagram if the
system is heated or cooled?
33.33、 What mechanisms can cause the entropy of a control volume to change?
(A) Heat interaction (B) Work interaction
(C) Irreversibility (D) Mass flow in or out
34.34、 In Figure 34, two tanks are connected by a valve. One tank contains 2 kg of carbon monoxide
at 77°C and 0.7 bar. The other tank holds 8 kg of the same gas at 27°C and 1.2 bar. The valve is
opened and the gases are allowed to mix while receiving energy by heat transfer from
surroundings. The final equilibrium temperature is 42°C. Using the ideal gas model
p mRT V = /
and the constant volume specific heat Cv=0.745 kJ/kgK, which of the following
statements is correct? (A) The final equilibrium pressure is 5.0 bar, (B) the final equilibrium pressure is 1.05 bar,
(C) the heat transfer rate is 37.25 kJ, (D) the heat transfer rate is 47.25 kJ.
35.35、 Please determine the force in each member of the truss shown below and identify which of the
following statements are correct? (A)FBD = FEF = 0 N (B) FCF = 32.5 kN (tension)
(C) FAD = 5 kN (tension) (D) FCD = 30.0 kN (compression).
44.44、 The boundary layer flow over a flat plate with zero pressure gradients is shown in Figure 44.
The control volume is defined as dashed line a-b-c-d and the depth is defined as w. Ahead of
the plate the velocity is uniform, U. The velocity distribution across cd is approximated by , here denotes the boundary layer thickness. Which of the
following statements is correct? (A) the mass flux across bc equals , (B) the mass flux across ab equals ,
(C) the mass flux across cd equals , (D) the mass flux across bc equals