Quiz Preparation – UMD Racing e.V.

Quiz „General Engineering“

1 / 10

An air stream

dot{M}_L = 5.5 kg/s,

cp_L=1 kJ/(kgK)

is to be heated in a plate heat exchanger from

θ_L′=20∘C

θ_L′′=150∘C

. For this purpose, a flue gas stream

dot{M}_R = 7.22

cp_R=1.1 kJ/(kgK)

with a temperature of

θ_R′=300∘C

is available. The overall heat transfer coefficient is

W/(m^2*K)

.
What is the required heating surface AAA if the fluid streams are arranged in counterflow?

a. 328,1 m^2

b. 314,12 m^2

c. 281,7 m^2

2 / 10

You would like to drink a cup of very hot coffee with milk early in the morning, but you
are in a hurry and have only 5 minutes until you have to leave for work. At which time
after brewing should you add the cold milk to the coffee and stir in order to decrease the
temperature of the mixture as much as possible:
a) 0 minutes (immediately),
b) 2 minutes, or
c) 4 minutes?
Suppose that the stirring can be done instantaneously and that you need the last one
minute for drinking.

brew temperature C = 80 ◦C, temperature of milk = M = 10 ◦C, room temperature
0 = 20 ◦C, volume of coffee VC = 300 ml, volume of milk VM = 100 ml, specific heat
capacity of coffee cC = 4180 J/(kgK), specific heat capacity of milk cM = 3500 J/(kgK).

Please enter only the letter of the corresponding answer

a. 2 mins

b. 4 mins

c. 0 mins

3 / 10

In a cylinder, air is compressed isothermally at ambient temperature (

θ_U=20∘C)

p_{1} = 0.1 MPa

p_{2} = 0.5 MPa

Calculate the change in the specific entropy of the air in the cylinder.

Round to two decimal numbers sperated by a point. Input in J/(kgK). (Example -365.26)

4 / 10

Calculate the pull force on the plate in Newton. Round to 2 numbers seperated by a point (exanple: 9.13)

5 / 10

Three inductors are connected as shown in the following figure:

Given that L1 = 2L2, find L1 and L2 such that the equivalence inductance is L = 0.7 H.
Give your answers in Henry, rounded to three decimal places separated by a comma (L1, L2)

6 / 10

A cantilever is subjected to forces

. Determine the bar force

F_{S 8}

Given F1=F4=F, F2=F3=2F, a

a. 7.27F

b. 2.85F

c. -6F

7 / 10

During last year acceleration a top speed of 100 km/h was reached. Due to big improvements in the new drivetrain, the new vehicle reaches a top speed of 120 km/h. The aerodynamics chief has some worries about the stability of the rear wing bracing due to the higher aerodynamics load. Given the geometry below, by how much % does the bearing force in point A change in comparison to last year? (The aerodynamic package did not change and therefore some values can be assumed for both vehicles). Give answer rounded to one decimal place.

CL=3.8 CD=1.2 A=1 m² rho=1.1 kg/m³ L1=50 mm L2= 100 mm H1= 125 mm H2= 165mm

8 / 10

Your team is the first car at the design event during FSN2022 and it’s quite cold for this time of the year, 12 degrees C. To impress the judges, you decide to make some tea for them. What is the minimum required time to prepare the tea, knowing that you have to boil 4 tea cups of 370ml each and you have an electrical heater with a power of 500W. Give your answer to the nearest whole number in secs.

9 / 10

A ball at a height of 20ft on Earth with a gravitational field strength of 9.81 N/kg, gained 284 J of gravitational potential energy. Calculate the mass of the ball. Give answer to two decimal place in kg.

10 / 10

A helicopter of mass 4200 kg is carrying a crate using a light extensible rope. The crate has a total mass of 800 kg, including its contents. The helicopter and crate are accelerating upwards at 2.0 ms^-2. What is the tension in the rope? Use gravititational field strength g is 9,81 N/kg. Air resistance can be ignored. Give answer to nearest whole number in Newtons

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