WE 1311 Final exam
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WE 1311 Final Exam
Section I Mechanics
1) Define the velocity vector and the acceleration vector for a particle of mass m following a position vector )(tr
v
a) , 2
2
dt
rd v
r r
= dt
rd a
r r
= b) , dt
rd v
r r
= 2
2
dt
rd a
r r
= c) Integrals of )(tr v
2) A particle moves in a circle of radius r with constant celerity v . Identify the formula for its angular celerity ω : a) vr=ω b) rv /=ω c) rv /2 =ω d) none of those
3) For the previous problem, the corresponding formula(s) for the magnitude of the linear acceleration is (are):
a) ra 2ω= b) rva /2= c) both
4) True or false? First Newton’s Law: “If no net force acts on a body its acceleration is zero”
5) Identify the proper definition of the SI energy unit a) 1 N = 1 kg m/s2 b) 1 J = 1 Nm c) 1 J = kg x °C
6) What is the formula for the kinetic energy of a particle?
7) True or false? Friction forces are conservative
8) For a non-viscous and incompressible fluid in a steady and non-rotational flow, the Bernoulli’s Equation holds. Identify its proper mathematical expression:
a) constvghp =++ 2 2
1 ρρ b) nRTvghp =++ 2
2
1 ρρ c) AFp /=
9) The figure below shows the lift and drag forces on an airfoil. Explain the physical origin of both forces.
10) Identify the proper statement:
a) Wind turbine convert the potential energy in the wind in electric energy b) Wind turbine convert the chemical energy in the wind in electric energy c) Wind turbine convert the kinetic energy in the wind in electric energy d) None of the above
Section II Thermodynamics
11) Convert a temperature of – 40 °C to Fahrenheit degrees.
12) Enounce the First Law of Thermodynamics and its mathematical expression
13) Enounce the Second Law of Thermodynamics
14) Identify the proper mathematical statements about the ideal gas model:
a) 0|| =
∂ ∂
= ∂ ∂
=
TT V
U
p
U
nRTpV
b) 0|| ≠
∂ ∂
= ∂ ∂
>
TT V
U
p
U
nRTpV
c) nRT
V
U
p
U
RTpV
TT =∂ ∂
= ∂ ∂
=
||
2
15) Define what is entropy and enounce the Second Law of thermodynamics using this concept
16) Define what is exergy
Section III Electromagnetism
17) Identify the proper expression for the voltage unit:
a) s
A V
1
1 1 = b)
C
J V
1
1 1 = c)
A
J V
1
1 1 = d) none of the previous
18) Identify the proper expression for the current intensity unit:
a) s
C A
1
1 1 = b)
V
C A
1
1 1 = c) sCxA 111 = d) none of the previous
19) What is the general expression for electrical power? What is its unit?
20) Enounce the Faraday’s Law of Induction
Bonus
21) Explain how a wind turbine transfers the different types of power, starting with the natural resource (the wind) and ending with the output of energy. Use the figure below
to guide your reasoning.
