Quiz Preparation – UMD Racing e.V.

Quiz „General Engineering“

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1. Unit: kg/(m^3), to decimal number seperated by: . (exp. 15.3), write only the number in the field below

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2. In a gas pipe, the gas pressure pG is measured using a U-tube manometer connected at the bottom. Above the meniscus of the measuring liquid (mercury with density ρQ) on the gas side, there is a column of water with height h₂ and density ρW.
Question:
What negative pressure △pU (vacuum) exists in the pipe compared to the external pressure p₀?

Result in Pa, two decimal numbers seperated by a point (exp. 15.3). Do not put the Unit in the field below.

3 / 10

3. 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)

4 / 10

4. Calculate the Normal force on the rear left tyre during the first skidpad lap. You can assume, that your vehicle is in a steady-state condition and that there is no longitudinal acceleration. Further it can be assumed, that all 4 wheels have a lateral grip coefficient of 1.4. You can use the centerline radius stated in the rules. Following information regarding the vehicle are given. Give answer to nearest whole number in Newtons.

m = 220 kg

Cl = 3.8

A = 1 m^2

Rho = 1.1 kg/m^3

Wheelbase: L = 1.53

Trackwidth:t = 1.2 m

Height of CG: h = 0.2 m

Weight distribution/COP: 50%

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5. Calculate the force Fc working at point C. Give answer in kN rounded to one decimal place.

Forces at point A: Rax = 3kN, Ray = 9kN, Ma = 10kN/m

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6. A racing car rolls to a stop on a horizontal course with an initial speed of v. It decelerates
only by friction with a rolling resistance of μF, which is supposed to be independent of
the current velocity.
What is the distance s the car needs to stop?
v = 230mph, μF = 0.17, g = 9.81 m/s2.
Give your answer in meters, rounded to four significant places.

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7. Calculate the cornering speed during Skidpad (you can use the centerline radius in the rules) using following information:

μ_y = 1.4, m = 240 kg, c_L = 3.2, A = 1 m^2, ρ = 1.1 kg/m^3

It is assumed, that there is no weight transfer and all 4 tires are at the optimal grip level. Answer in m/s rounded to one decimal place.

8 / 10

A metal piece heated to

θ_1,M=1000∘C

with a mass of

M_M=6.5 kg

was cooled in a completely heat-insulated iron container filled with water. The mass of the water in the container is

M_W=10 kg

and the mass of the container is

M_B=2 kg.

The initial temperatures of the water and the container were the same and amounted to

θ_1,W=10∘C

. After complete thermal equilibrium between the immersed metal piece, the water, and the container, a temperature of

was established.
What is the average specific heat capacity of the metal piece

c

in the temperature range between

and

Input the result in kJ/(kg*K), round to 3 decimal numbers sperated by a point (example: 0.136).

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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. 281,7 m^2

b. 314,12 m^2

c. 328,1 m^2

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10. Before the endurance you pump nitorgen in your tires at a temperature of 20°C and 0.7 bar relative pressure. Knowing, that during the endurance the maximal tyre temperature will be around 60°C, what will be the maximal relative pressure of the tyre? Give answer in bar to two decimal places.

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