1. Density is a measure of mass per unit volume. Common materials like water, wood, oil, and gasoline have different densities that determine whether they will float or sink. 2. Specific gravity is a ratio of a material's density to the density of water. It is a dimensionless number that can be used to compare densities of materials. 3. An object's density determines whether it will float or sink in a fluid. Less dense objects float, while more dense objects sink due to differences in buoyant forces versus gravitational forces.

1. 1. GOSTOTA
2. SPECIFIČNA TEŽA
3. VZGON IN PLAVANJE
4. TLAK
][ 3
m
kg
V
m
=ρ 1 2
m1 = m2
21
21
VV <
> ρρ
nalogeSVINEC > VODA > LES > OLJE > BENCIN
][ 3
m
N
V
Fg
=σ 33
33
0001010
10001
m
N
dm
N
m
kg
dm
kg
VODE
VODE
==
==
σ
ρ
10⋅= ρσ
naloge
][NVF vodevodeV ⋅= σ
Fv
Fg
Fv
Fg
Fv
Fg
Fp
Fv
Fg
Fv
Fg
MIRUJE SE GIBLJE
][ 2
Pa
m
N
S
F
p ==
hp ⋅= σ
2
2
1
1
S
F
S
F
=
naloge
slika
h h h
VODA OLJE

2. a) PODATKI:
m = 50 kg
V = 10 dm3
RAČUN:
?=ρ
3
3
5
10
50
dm
kg
dm
kg
V
m
=
=
=
ρ
ρ
ρ
b) PODATKI:
RAČUN:
?
1
2,1
3
3
=
=
=
m
dmV
dm
kg
ρ
kgm
dm
dm
kg
m
Vm
2,1
12,1 3
3
=
⋅=
⋅= ρ
c) PODATKI:
RAČUN:
?
2
2,1 3
=
=
=
V
kgm
dm
kg
OLJAρ
3
3
5,2
8,0
2
dmV
dm
kg
kg
V
m
V
=
=
=
ρ
1. GOSTOTA
][ 3
m
kg
V
m
=ρ 1 2
kazaloSVINEC > VODA > LES > OLJE > BENCIN
m1 = m2
21
21
VV <
> ρρ

3. 2. SPECIFIČNA TEŽA
][ 3
m
N
V
Fg
=σ 33
33
0001010
10001
m
N
dm
N
m
kg
dm
kg
VODE
VODE
==
==
σ
ρ
10⋅= ρσ
3
3
5
10
500
dm
N
o
dm
N
V
F
=
=
=
σ
σ
σ
NF
dm
dm
N
F
VF
12
112 3
3
=
⋅=
⋅= ρ
3
3
5,2
8
20
dmV
dm
N
N
V
F
V
=
=
=
σ
a) PODATKI:
m = 50 kg
V = 10 dm3
RAČUN:
?=σ
b) PODATKI:
RAČUN:
?
1
12
3
3
=
=
=
F
dmV
dm
N
σ
c) PODATKI:
RAČUN:
?
202
8 3
=
=→=
=
V
NFkgm
dm
N
OLJAσ
kazalo

4. 3. VZGON IN PLAVANJE
][NVF vodevodeV ⋅= σ
Fv
Fg
Fv
Fg
Fv
Fg
Fp
Fv
Fg
Fv
Fg
MIRUJE SE GIBLJE
kazalo

5. 4. TLAK
][ 2
Pa
m
N
S
F
p ==
Pa
m
N
m
N
S
F
p
44
5
20
2
2
==
=
=
σ
σ
Pap
m
N
S
F
p
nogieni
nogieni
60
15
900
_.1
2_.1
=
==
a) PODATKI:
F = 20 N
S = 5 m2
p = ?
RAČUN:
Pap
m
N
S
F
p
OBEH
OBEH
30
15
450
.1
2.1
=
==
b) PODATKI:
RAČUN:
?
?
15
90
_.1
_.1
2
=
=
=
=
nogaobeh
nogieni
STOPALA
p
p
dmS
kgm
kazalo
hp ⋅= σ
2
2
1
1
S
F
S
F
=h h h
VODA OLJE

6. 4. TLAK
][ 2
Pa
m
N
S
F
p ==
barbarbarppp
barkPap
Pa
m
N
p
m
m
N
p
hp
x 211
1100
000100000100
1000010
0
2
3
=+=+=
==
==
⋅=
⋅= σ
a) PODATKI:
h = 10 m - globina, od površja dol
σ = 10 N/dm3
=10 000 N/m3
p
x
= ?
RAČUN:
b) PODATKI:
RAČUN:
?p
m
N
00010
m
kg
1000
dm
kg
1
m45h
x
3
10
33
=
= →==
=
⋅=
σρ ρσ
kazalo
hp ⋅= σ
2
2
1
1
S
F
S
F
=h h h
VODA OLJE
barbarbarppp
barkPap
Pa
m
N
p
m
m
N
p
hp
x 5,55,41
5,4450
000450000450
4500010
0
2
3
=+=+=
==
==
⋅=
⋅= σ

7. a) PODATKI:
m2= 120 kg > F2= 1200 N teža avtomobila
S2=100 dm2
S1=10 dm2
m
1
= ?
RAČUN:
4. TLAK
][ 2
Pa
m
N
S
F
p ==
2
12
1
S
SF
F
⋅
=
kazalo
hp ⋅= σ
2
2
1
1
S
F
S
F
=h h h
VODA OLJE
F1
S1
F2
S2
kgmNF
dm
dmN
F
1210:120120
1
10120
11
2
2
1
==→=
⋅
=