Fundamental Concepts Tutorial 1 to answer just click on the button or image related to the answer.
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Transcript of Fundamental Concepts Tutorial 1 to answer just click on the button or image related to the answer.
what is their weight (in kN) on earth ?
(on Earth g = 10 m/s2 approx)
a person has a mass of 70 kgs.
Question A1
700 kNa
0.7 kNb
70 kNc
what is their weight (in kN) on a roller coaster ?
(on roller coaster grc = 3 x g m/s2 approx)
a person has a mass of 70 kgs.
Question A2
2.1 kNa
210 kNb
21 kNc
what is their weight (in kN) on the moon ?
(on the moon gm = 0.17 x g m/s2 approx)
a person has a mass of 70 kgs.
Question A3
1.2 kNa
120 kNb
0.12 kNc
what is the force acting down on surface S ?
given two blocks A, and Bon a surface S.
Question A4a
200 kNa
3 kNb
300 kgc
ABS
mass (A) = 100kg
mass (B) = 200kg
what is the force acting up on block B ?
given two blocks A, and Bon a surface S.
Question A4b
2 kNa
3 kNb
1 kNc
ABS
mass (A) = 100kg
mass (B) = 200kg
what is the pressure on surface S ?
given two blocks A, and Bon a surface S and that block B is 200 x 150 mm
Question A4c
66.6 Paa
1000 kPab
100 kPac
ABS
mass (A) = 100kg
mass (B) = 200kg
what is the moment at A ?
given the force of 2kNacting as shown
Question A5a
5 kNma
10 kN/mb
10 kNmc
B
A
C
5m
2kN3m
what is the moment at B ?
given the force of 2kNacting as shown
Question A5b
6 kNma
3 kN/mb
1.5 kNmc
B
A
C
5m
2kN3m
what is the moment at C ?
given the force of 2kNacting as shown
Question A5c
2 kNma
2 kN/mb
0 kNmc
B
A
C
5m
2kN3m
what have we learnt ?
so in general, if a point lies on the line of action of a force
Question A5d
nothinga
the moment of a force about a point lying on the line of action of the force is zero
b
which system of forces will provide equilibrium?
given the system shown
Question A6
a b
10kN
10kN
10kN
10kN
10kN
10kN
10kN
10kN
14.1kN
either a or bc
find forces F2 and R1 so as to provide equilibrium?
given the system shown
Question A7F2= ? kN F1= 12kN
A B C3m 1mR1= ? kN
F2 = 4 kNm and R1 = 16 kNma
F2 = 4 kN and R1 = 16 kNb
F2 = 36 kN and R1 = 48 kNc
what is the purpose of structure in buildings?
Question B1
to provide the fabric of the space enclosurea
to organize the elements of the buildingb
to resist all the forces acting on the building and transfer them to supports (the ground)
c
all of the aboved
a and ce
what are the three main considerations when dealing with structure?
Question B2
aesthetics, spaces and materialsa
stability, strength and stiffnessb
dead loads, live loads and supports c
Question B3
show answera
finishb
given the post-and beam arrangement as shown, and assuming pin-joints,describe three ways of stabilising it.
draw and name them
let me try again
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Weight is a force. Weight = Mass x g where g = 10 m/s2 on earth1kg of mass = 10N of force on earth. 100kg of mass = 1kN weight on earth
next question
enough !
Weight is a force. Weight = Mass x g where g = 10 m/s2 on earth1kg of mass = 10N of force on earth. 100kg of mass = 1kN weight on earth
0.7 kNso on Earth (g = 10 m/s2) Weight = 70 x 10 /1000 =
next question
enough !
Weight is a force. Weight = Mass x g where g = 10 m/s2 on earth
and 30 m/s2 on a roller coaster1kg of mass = 30 N of force on roller coaster. 100kg of mass = 3 kN weight on roller coaster
2.1 kNso on roller coaster (g = 30 m/s2) Weight = 70 x 30 /1000 =
let me try again
let me out of here
Weight is a force. Weight = Mass x g where g = 10 m/s2 on earth
and 30 m/s2 on a roller coaster1kg of mass = 30 N of force on roller coaster. 100kg of mass = 3 kN weight on roller coaster
next question
enough !
Weight is a force. Weight = Mass x g where g = 10 m/s2 on earth
and 1.7 m/s2 on the moon1kg of mass = 1.7N of force on the moon. 100kg of mass = 0.17kN weight on the moon
0.12 kNso on the moon (g = 1.7 m/s2) Weight = 70 x 1.7 /1000 =
let me try again
let me out of here
Weight is a force. Weight = Mass x g where g = 10 m/s2 on earth
and 1.7 m/s2 on the moon1kg of mass = 1.7N of force on the moon. 100kg of mass = 0.17kN weight on the moon
next question
enough !
both blocks A and B are acting on surface S
3000 Nso the total weight on surface S (on earth) = (100 +200) x 10 =
3 kN =
let me try again
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both blocks A and B are acting on surface S
don’t forget that it’s force we are after, not massyou must convert the total mass to a force
next question
enough !
for every force there is an equal and opposite reaction
since the total force acting down is 3 kN, the force acting up, i.e. the reaction must be 3kN
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remember:for every force there is an equal and opposite reaction
next question
enough !
pressure = force / area, P = F / A
so, working in kNs and metres, P = 3 / (0.2 x 0.15) = 100 kN/m2
since 1 kN/m2 = 1 kPa, 100 kN/m2 = 100 kPa
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pressure = force / area, P = F / A
so think about what the total force down is and what the area is.work in kNs and metres
next question
enough !
moment = force x distance, M = F x D
yep! moment is force x distance, so the moment is 2 x 5 = 10 kNmsince it is force x (multiplied by) distance the units are kN x m, i.e kNm
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so think what the force is and what the distance is.The distance is the perpendicular distance from the point to the force
work in kNs and metres
moment = force x distance, M = F x D
let me try again
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so think what the units areforce multiplied by – not divided by distance
moment = force x distance, M = F x D
next question
enough !
moment = force x distance, M = F x D
yep! moment is force x distance, so the moment is 2 x 3 = 6 kNmsince it is force x (multiplied by) distance the units are kN x m, i.e kNm
let me try again
let me out of here
so think what the force is and what the distance is.The distance is the perpendicular distance from the point to the force
Think of the units. Work in kNs and metres
moment = force x distance, M = F x D
next question
enough !
moment = force x distance, M = F x D
yep! moment is force x distance, so the moment is 2 x 0 = 0 kNmsince it is force x (multiplied by) distance the units are kN x m, i.e kNm
let me try again
let me out of here
so think what the force is and what the distance is.The distance is the perpendicular distance from the point to the force
Think of the units. Work in kNs and metres
moment = force x distance, M = F x D
THINK !!
next question
enough !
moment = force x distance, M = F x D
so if the point lies on the line of action of the force, the distance from the point to the force must be 0and hence the moment must be 0
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so think what the distance is when the point lies on the line of action of the force.
moment = force x distance, M = F x D
next question
enough !
in a) the vertical forces are equal and opposite and the horizontal forces are equal and oppositein b) the resultant force of the horizontal and vertical forces would be 14.1 kN, so the equilibrant force (the force providing equilibrium) would be 14.1 kN (equal and opposite to the resultant force)
both systems are in equilibrium
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the vertical forces are equal and opposite and the horizontal force are equal and opposite
so it is in equilibrium but this is not quite the right answer
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the equilibrant force is equal and opposite to the resultant force of the horizontal and vertical forces
so it is in equilibrium but this is not quite the right answer
next question
enough !
clockwise moments about B = 12 x 1 = 12 kN anti-clockwise moments about B = F2 x 3so F2 x 3 = 12 kN F2 = 4 kNsince ΣV = 0, R1 = 4 + 12 = 16 kN
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take clockwise moments about B , then take anti-clockwise moments about B
then use the equation ΣM = 0 (sum of clockwise = sum of anti-clockwise)
How did you get this?
Don’t guess!!
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in general terms, structure does deal with the organization of complex objects but we are concerned with structure in the domain of forces
next question
enough !
Stability - equilibrium building must not move - up, sideways or overturn all forces and moments must balance
Strength building & elements must not break / collapse
Stiffness / functionality building & elements must continue to serve their purpose, must not deform too much
the three Ss
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we are concerned with structure in the domain of forces not with architectural form or spaces
a) cross-bracing
b) knee-bracing
c) rigid joints
d) solid infill (shear panels)
e) build-in posts
any of these will do
that’s it