group quiz 1 answers

8/2/2019 Group Quiz 1 Answers

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ME 63 THUV/WFVW 2nd

Semester AY 2010-2011 Group Quiz Number 1.

FOR THUV: Submit your answers on Friday before 12 PM at my Pigeon Hole at the ME Department.

Problem 1:

The water in a tank pressurized by air, and the pressure is measured by amultifluid manometer as shown in the figure below. The tank is located

on a mountaion at the altitude of 1400 m where the atmospheric

pressure is 85.6 kPa. Determine the air pressure in the tank if h1=0.1 m,

h2=0.2m, and h3= 0.35m. Take the densities of water, oil and mercury to

be 1000 kg/m, 850 kg/m3 and 13600 kg/m3, respectively.

3

3

3

1 2 3

1 1 2 3

1

:

=85.6 kPa=85600 Pa

1000 /

850 /

13600 /

0.1 ; 0.2 ; 0.35

:

[(1000)(9.81)(0.1)] [(850)(9.81)(0.2)] [(13600)(

atm

water

oil

mercury

water oil mercury atm

Given

P

kg m

kg m

kg m

h m h m h m

Solution

P gh gh gh P

P

1

9.81)(0.35)] 85600

129646.9 129.6469P Pa kPa

Problem 2:

Can you carry 1 m of liquid water? Explain your answer

Solution:

The density of water is 1000 kg/m, Therefore m= V =1000kg/m (1m)= 1000 kg,You cannot carry

that in the standard gravitational field.


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Problem 3:

A cannon ball of 5 kg acts on a piston in a cylinder of 0.15 m diameter. As the gun-powder is burned a

pressure of 7 MPa is created in the gas behind the ball what is the acceleration of the ball if the cylinder

(cannon) is pointing 40 up relative to the horizontal direction.

1

2

2

2

( ) sin 40

(.15 )(7000 101) (0.5)(9.81)(0.6428)

4

= 121.9 kN-31.52 kN=121.87 kN

121.87a= 24374

5

24374

oF ma P P A mg

ma

F m

m s

ma

s

Problem 4:

You dive down 5 m down in the ocean. What is the absolute pressure there?

3 2

0

997 / (9.81 / )(5 )

48903 48.903

101.325 48.903

150.228

ocean

ocean

ocean

Solution

P g h

P kg m m s m

P Pa kPa

P P P

P

P kPa

You climbed up a hill of 250 m elevation, what is the pressure you feel up there?

3 2

0

3

1.17 / (9.81 / )(250 )

2869.425 2.869425

101.325 2.869425

98.455575

* 1.17 /

hill

hill

hill

air

Solution

P g h

P kg m m s m

P Pa kPa

P P P

P

P kPa

note kg m


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Problem 5:

Complete the Table

Celsius Farenheit Kelvin Rankine

37 98.6 310.15 558.27

44.44 112 317.5944 571.67

71.85 161.33 345 621

68.51667 155.33 341.667 615

100 212 373.15 671.67

Problem 6:

What is the net force acting on a car cruising at a constant velocity of 70 km/h (a) on a level road and (b)

on an uphill road?

Solution:

The car is cruising at a constant velocity, meaning zero acceleration thus the net force for both cases

are zero.

Problem 7:

A hydraulic lift has a maximum pressure of 1250 kPa. What should be the piston-cylinder diameter be so

it can lift a mass of 40390 kg?

F=PA=mg

A= 2r =2

4

D;PA=P

2

4

D=mg

2 4mgDP

40390 (9.81)2 2

1250 10000.6352892157

mg kgD

P xD

group quiz 1 answers

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