Quiz Preparation – UMD Racing e.V.

Quiz „General Engineering“

1 / 10

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.

2 / 10

Frage

a. Depends on y

b. Nein

c. Yes

3 / 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. 314,12 m^2

b. 328,1 m^2

c. 281,7 m^2

4 / 10

An object is fired vertically upwards from the ground at time t = 0 s in still air at a speed of 9.6 m/s. On the way up, what is the height of the object above the ground when it has a speed of 1.9 m/s. At what time does it reach this height on the way down? Give both answers separated by a comma to one decimal place.

5 / 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).

6 / 10

in cm^3, round to decimal numbers sperated by point (13.5) no unit int the answer

7 / 10

The previous season you could recuperate only 25% of your initially stored energy, but this season a big improvement in your drivetrain allows you to recuperate 63% of the initially stored energy. Knowing that you had 9.6 kWh of energy in your accumulator during the last season, how much energy must your new accumulator have, if you assume, that it’s the same length and speed? Give answer in kWh to one decimal place.

8 / 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. 4 mins

b. 2 mins

c. 0 mins

9 / 10

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

10 / 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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