dynamic of rotation

8/9/2019 Dynamic of Rotation

http://slidepdf.com/reader/full/dynamic-of-rotation 1/9

DYNAMIC of ROTATION

1. Two subtances A and B with mass 10 kg and 8 kg connected by a pulleywith mass 2 kg.

So the accelaration of A and B is«

Answer :

W1 = m.g = 10. 10 = 100 NW2 = m.g = 8. 10 = 80 N

7F = 20 N

205,1

2.2

118

20

sm

Kmm

F a

k tot

!

!

!§

2. At a wheel that has inertial moment 7 kgm2 is in rest, is exerted by a force moment of 40

Nm. So the angular velocity when force moment exerted in 4 second is«

Answer :

EX

. I !

¹ º

¸©ª

¨ !

t I t 0

[[X

srad

t

t

85.22

4

0740

!

¹ º

¸©ª

¨ !

[

[

3. The beam PS with length 3 m and divided into three parts that same length PQ = QR =

RS. So the torsion at point A is«

FP=15 N FR = 20 N

P Q R S

FQ= 15 N FS= 5 N

Answer :7X S = X P + X Q + X R

= - FPLP + FQLQ + FR LR

= - 15. 3 + 15. 2 - 20. 1

= - 35 Nm

4. Look at the picture !

A solid sphere with velocity 25 m/s r otary until the to p of thehills. So the high of the hills is«

v = 25 m/s h = 43.75 mk

ghv

!

1

2

5

21

.10.225

!h



Answer :


60030

0T1= 24 N. m = ?

T1 Answer :

90sin150sin

1 wT !

1

2

1

240 w! w = 480 N m= 48 kg


A solid sphere r otary f r om the to p of the hills.E = 53

o. So the accelaration of the solid sphere

is «

Answer :53o

7

40

15

2

53sin10

1

sin 0

!

!

!k

g a

E


A B FA= ? FB = ?

w = 440 N

wAB = 200 N

Answer : 7X = 0

FA. AB = WAB.2

1AB + W.

4

1AB

FA= 200 . 2

1

+ 440 . 4

1

FA= 210 N

FB = W ± FAFB = 640 ± 210 = 430 N


mAB = ?

m



w

A 5 m B

m = 15kg

Answer : oT A!§

ABW ABW box AB

.2

1. !

.0.2

.0. ! AB M kg M

AB3!

9 Look at t e pict re !

ind t e tension in t e upper cable !

7X =

5 m w1l1 + w l = T sinE l¡

m 15 + 4 = T /5 4T = 6 5 N

4 m

N15 N

1 A cylinder wit a moment of iner tia Io r otates wit angular velocity [o, A second cylinder

wit moment of iner tia I1 initially no r otating dr o ps onto t e f irst cylinder and two reach

the same f inal angular velocity [f . ind [f !

Answer :

L1 = L2

Io.[o = Io. [f + I1.[f

Io.[o = [f (Io+ I1)

1¢

¢ ¢

I I

I f

£

¤

¤

FLUIDS

11. A hydraulic pump is in the form of two cylinders. Each cylinder is 14 cm and 24 cm. if the small piston is pressed with a for ce of 5 N, the the for ce which resulted by the big

one is«Answer :

2

2

1

1

A

F

A

F !

2

2

2244/1144/1

50

T T

F ! 2 = 146.9 N



12. The water f low in a water-tap that its section area is 1 cm2

with velocity 1 m/s. Thewater is distr i buted by a plastic pi pe which its end is connected to a sprayer with section

are .1 cm2 has velocity of «

Answer :

A1 v1 = A2 v2 1 . 1 = ,1 . v2

v2= 1 m/s

1 . Look at the picture !

P = ? Answer :

1 cm P = Po + h

= 76 + 1

= 86 cmHg

Hg

14. A substance when it is deli berated in air 6 N, but when it is deli berated in liquid 4,2 N. If

density of the substance is kg/m¥

. The density of f luid is«

Answer : w = m.g6,0

!!v

m V

6 = m.10

m = 0,6

§ ¦ 0 Fy

b A w F T !

T w F b A§

,,

! f V

̈

mkg

© ! V

15. Look at the picture ! 2= 25 N

m = ?Aq = 20 cm2

5 m

A p= 600 cm2

Vc = 900 kg/cm

Answer :

P1 = P2

246

b f w g V



gh A

F

A

F c

V!

2

2

1

1

2

2

1 A

F gh

A

m g c

! V

44 1020

25

5.10.90010600

10. v!v

m

m = 345 kg


1,25 m

20 m

X = ?

Answer : ghv 2!

25,1.10.2!v

smv 5!

2

2

1 gt y ! t V X X .!

2.10.2120 t ! m

102.5 !!

2!t

17. An ice a f loating in the sea. If the density of water is 1,5 gr/cm3

and the density of ice 0,9

gr/cm3. So, the volume of ice that has hide in the sea equal with « volume that shown.

Answer : g m F b A.!

bbb f f f g g V V !

f

bb

f

V V

V

V!

b f V V 5,19,0! b f V V

53! the volume of ice that has hide in the sea = bV

52

18. A pi pe with diameter 30 cm is connected with other pi pes with diameter 10 cm on

hor izontal position. If the velocity of the water in big pi pe is 1 m/s and pressure is 105

N/m2, so the pressure in small pi pe is« ( Vwater = 1gr/cm

3)

A1 v1 = A2 v2

9 . 1 = 1 . v2

v2= 9 m/s



ghv P ghv P V V V V !2

22

2

112

1

2

1

2

2

25 9.1000.2

11.1000.

2

110 ! P

105

+ 500 = P2 + 40500

P2 = 60000 N/m2


Figure above shows the cr oss-section of a dam a

with a depth of 22 m. What is the pressure of the

water at the base of the dam if the density of water

is 1000 kg/m3

?

22 m

Answer :Ph = V g h

= 1000 . 10. 22= 2,2. 10

5Pa


Vt= ?

7 cm

3 cm

Answer :Pt= Pa Vtgtht = Vaga ha

Vt . 10 = 1 . 7

Vt = 0,7 gr/cm3

TERMODYNAMICS

21. Ideal gas in 27oC warm by isokhor ik until the pressure become twice f r om begin. The

ratio of magnetic energy before warmed and af ter warmed is«

Answer :2

2

1

1

T

P

T

P !

2

1

1

1 2

T

P

T

P ! T2 = 2 T1

1

2

1

2

.2

3

.23

T k

T k

Ek

Ek !

1

2

1

2

T

T

Ek

Ek !

2

1

1

2 ! Ek

Ek Ek 1 : Ek 2 = 2 : 1

22. A machine calor work with carnot cycles. If high temperature resevoir 400 K and

efficiency 40 %. If reservoir has temperature 640 K, the efficiensy is«



Answer : %10011

21 ¹¹

º

¸©©ª

¨!T

T L %1001

'

1

2'

¹¹ º

¸©©ª

¨!T

T L

40014,0 2T ! %100

640

2401 ¹

º

¸©ª

¨!

K T 2402 ! %5,62!

23. The diagram below shows the change in pressure and volume of an ideal gas thr ough two

path PQR and PSR. For the change thr ough the path QR, the heat absorbed by the gas is30 joule. What is the heat absorbed by the gas for the change thr ough the path PSR ?

105

Pa

Answer : wU Q (!

5 Q R V P V P Q ((!2

3

2 P S J Q 2510.5.10.210.5.10.22

3 5555 !!

10-5 m3 1 6

24. Helium gas has volume 2 liter at 1 atmpressure and 27oC temperature is heated until the

pressure and and the becomes twice its initial, then its final tempertusre is«

Answer :2

22

1

11

T

V P

T

V P !

2

4.2

300

2.1

T ! T2 = 1200 K

25. The temperature in a r oom with air conditioner is -23oC and the temperature outside

27oC. Every 30 minutes pr oduce heat 3.10

6 joule. The electr icity is used for o perate air

conditioner is«

Answer :21

2

21

2

T T

T

QQ

Q

!

w

Q Kp 2!

250300

250

10.3 2

6

2

!

Q

Q

w

610.5,25 !

6

2 10.156 !Q 510.5!w 6

2 10.5,2!Q

watt

t

w P 43

5

10

36

110

18

5

1800

10.5!!!!

26. An air conditioner has Kp = 6,5 . If the high temperature resevoir is 27oC. How

temperature in the air conditioner ?

Answer :21

2

T T

T K p

!

2

2

3002

13

T

T

!



390015 2 !T

C K T o

132602 !!

27. An ideal gas in a cylinder have k inetic energy particle 4 Eo , if the k inetic energy becomes

Eo , temperature gas 6270C then its initial temperature is «

Answer :

1

2

1

2

.2

3

.23

T k

T k

k

k !

10

0 9004

T

K

E

E ! K T 2251 !

28. The temperature of the r oom is T kelvin. A particle of gas is moving at v velocity if thechange temperature is 15 T, then the velocity of particle becomes «

Ek =2

3K T

2

1

1

2

T

T

v

v!

K T mv2

3

2

1 2 !T

T 16!

m

K T v

3!

12 4vv !

29. The r oot mean square velocity of the molecules of an ideal gas at pressure P and volume

V is Cr. The gas is heated so that its volume becomes2

3V and its pressure becomes 6 P.

What is the new r oot mean square velocity of the gas molecules ?

Answer :

m

V P

m

V P

Vr m s

Vr m s

11

22

1

2

3

3

!

PV

V P Vr m s 2

36

Cr

2 ! C r Vr m s 32 !

30. A carnot machine with low temperature reservoir 27oC has efficiency 70 %. If the

efficiency becomes 80 %. The high temperature resevoir must becomes«

Answer :

%10011

21 ¹¹

º

¸©©ª

¨!T

T L %1001

1

22 ¹¹

º

¸©©ª

¨!T

T L

1

3001

10

7

T !

1

3001

10

8

T !

K T 10001 ! K T 500!( K T 15001 !



SMAN 10 PadangSchool Year

Name : Mujibur RahmanClass : XI IPA 2

Teacher : Mrs.Desmalinda

Final PROJECT of

PHYSIC

By:

dynamic of rotation

Documents