Ä
Ä
Ä
.
ill
BBI
2
I
CANDIDATE ID NUMBER: |__|_|_|_|_|_|_|_|
I
. 1
1
_·.‘_.1*
1
Ä
I
Ä
·
I
I
Ä
1 I
_ 1 I
UNIVERSITY OF GHANA ·
DEPARTMENT OF PHYSICS ·-
Ä
.
I
FIRST SEMESTER EXAMINATIONS: 2014/2015 ‘
I
.
.
Ä
PHYS 143: MECHANICS AND THERMAL PHYSICS (3 Credits)
—ATTEMPT ALL QUESTIONS
ÄI
I
I1 .
TIME ALLOVVED: TWO AND HALF HOURS
· ·
_I
Ä
I
*
·
·
Ä
_
Ä
ÄÄ
Ä
Instructions
.
~ .
PRINT your student ID number in the space provided at the top of each page.
Each question or partial statement is followed by five suggested answers or completions.
SelectI
*
I the best answer or completion and mark the corresponding bubble.
Ӏ I
*
. ÄI
Example
·
1
Ä
0. _A.
The SI unit ofmass is
N.
B. kg.
I:
1 1 1;.11.
1
I
1
C. g.
_
I
I
ÄI
?
I
Ä
I I
f
I
l9_1A_1 I-¤-11 1¤¤11¤iÖI‘
1E. w.
I
_
I
Y
’
1
1I
.
'
Values of Physical Constants
I Q_
I
s'2
’
Acceleration due to gravity
g = 9.81 m
_
·I
Ä—
‘
'
* 1 Molar mass ofHydrogen gas
—
'I
= 2 kg / kmol
Ä , . .‘ Ä
Ä
Ä
Molar mass of Oxygen gas
= 32 kg / kmol
‘
_Radius
of the Earth
RE = 6.37>< 106
mI
Mass ofthe Earth
ME = 5.98 >< 1024
kg*
kg‘2
Universal gravitational constant,
G = 6.67 >< 10*1 N m2
__
Ä
. _*
‘
‘
_1
‘
R = 8.3149 J mol" K4
NA= 6.02><1022 mol"
1kB = 1.38><10°23 J K"
Universal gas constant,
Avogadro’s
number
Ä
Bo1tzman11’s Constant
-*
*
I
IT
1 Ä4
_
EXAMINERS: DR. E. M. BAIDOE-ADEITEYE, DR. S. ATARAH, DR. H. A. KOFFI & MR. A. AMANKWAH
T
A
Ä;
PHYS 143: MECHANICS AND THERMAL PHYSICS
‘
1 .A
Ä
-
.
-’
'
Ä Ä Ä
Ä
‘
'
Page 1 of 11
..
1
'
11* Ä
2
II
I
CANDIDATEIDNUMBER:
2.
‘^
1 E B 11
Ä
1 D11 dg
42
11161 [c1_ [01 1 E
’1 B1 [C EÜÜEÜÜÜ
um IHIIIEIIHE
4
4
1
Illll 1
111.611111o
6
1....1..
.191...... . 1
.1 ¤l D 1 1.
1
ü
Bäläläc
26111Aä]
1118
*[
19
.1
C.1.
.1.,~
.
.9
B
E
V
[A
]‘l
ll
D11
1
·'
ät
E]
[D1 [1
A
113
[Q1
AB
EIIHE
~—
1
I
QB
.1.1...1.1.1..;.ä
1.
2
· ·_ «_
.1.. E .1.
I.1.
E1
1V
Ä-V
r '.
Ig
·l
. _
_·
_
;PHYS\43:MECi-IANICS Awon-x6RMALPuvsxcs
H. A. 1<om&MR. A.“ AMANKWA1-1
ExAM1r~1ERs;¤1>„.E. M. ßA1¤oE-A-DELEYE, DR. s. ATARAH, DR.
”"
‘
Q
Pagc20f11__
nv
CANDIDATE ID NUMBER:
··
.
Al.
The work done by a conservative force between two points is.
A
‘
·
.
/1*11 · ·
A. Always positive.
’
I
1_
1
time..
A A ” l B.. AlAways dependent upon the
1.
C. Always independent of the path.
·
1I1
·
gf
·
D. Zero.
A
_ ~” ""’"t
1E.
Never completely recoverable.
„
2. A woman runs up a flight of stairs. The gain in her gravitational potential energy is U. If she
runsA
'
1- .
1
up the samefstairs at twice the speed, what is her gain in potential energy?
1 1
A. iv
1A
.
B. %U
Ii
j
I _
A
1
U1 U
]
. . 1 ·* 1.1
.
..
1
1 D. ZU.;
1
1 1
*4U.·· 1
._
;1t
-12.*
I
A
Ä‘
.
i
3. A swinging simple pendulum is acted upon by theßfollowing forces:
A
I
1
AI.
force of gravity.
·
I
A1
i
1
II. air resistance.
A. A
1
1
·
A
·
A
%
1
·
III. tension in the cord.A
AA
Alt
A
A
AA
Which of these forces does no work on the pendulum? ·*
‘”
* 2 1A. Ionly
At
“A
°
B. II only
A
A
I
*
C. IandIIonlyA
_
__
‘
AA
‘
D. I, II and III
.
A
4
A
._ ° E.
' A l l
III only
AA
.
The work — energy theorem is valid for all objects or systems. _}
III. Hooke’”s law is a.fundamental law ofnature. ·
·” l
A
’
‘
'
‘1
**1
A. Iand II only
1
·
I
·
·
A
B. I and III only
C. II and·III only‘·
‘
1
A
” ‘
t
I
*
*5. In an elastic collision,
1
_}
A
'
·
A
1 D. kinetic is halved.
1 A
A
.
A
A1
A
E. kinetic is doubled.
A
.A
.
A
ft
I
PHYS 143: M.ECHANtCS' AND THERMAL BHYSICS i
A
tA„A
A.
EXAMINERS: DR. E. M.
BAIDOE-ADELEYE, DR. S. ATARAH, ADR. H. AI KQFFI & MR. A. AMANKWAH
1
1
..AA
, ° 1
AA
Page°3 61 11
A
1
·1
2
’ AQ
1,
D. 1, II and
11
AE. Ionly III
1
A
AA
A. kinetic energyis
conserved.t
1
B. kinetic energy is gained.
C. kinetic energy is lost.
1 A
A
U
4. Which ofthe following is not true?
1‘
AA
.-I.The 1magnitude of the normal force is not always equal to the magnitude of the
I
A
weight.Il.
·A
‘
A A·
A1
·‘
A'
.
· A A
A.
A
\_|;|+|__|__|__\__|__|
'
CANDIDATE IDANUMBER:
4
4
_ ~
.
. A . A
6. Which ofthe following is correct?
conserved.
kiAnetic energy is
'
A. °Whether a collision is elastic or not,
A
B. Impulse is a vector that takes same
‘
.
.4
direction as the initial velocity of the moving body.
momentum.
_ AD. The rate of change of force is the 'negative of
Y
0nYa body;
for a given force acting
Mass is directly proportional to acceleration
4
‘
4
-B_ .AKinetic.Aenergy. A .
1
· C. Momentrann.
A ‘4
A
‘
’
A -
D. Work.
N
L'
"
A
1
·
A. Moment of inertia.
‘
‘
motion is
7.4 The rotational analog of mass in linear
A
——Y
q
1. .A .
·
A _-
„
.
.
·
—
4
_
’
A
A
-
4 4
I
A A.
conserved.
A
is
momentum
is elastic or not,
coll_ision
a
Whether
C.
A
.A
A·‘4
·
A ·
A
~·
·
A
A A
.·
I
4
A AA
4
AA‘
*
E_ Tgyqpg
A
AAA
A4
a particle is
4 °A
8. The magnitude of the displacement of
Y
A
_
A.
4
A
A4
‘ 4°
travels.
—
A. larger than the distance the particle
A. _4
A
A
.
4
A1
travels.
44
particle
the
distance
the
than
smaller
B. always
A
the particle travels. .
°
—~—
C. larger than or equal to the distance
—
·
.
4
travels.
particle
the
distance
D. the same as the
A
·
4
the particle travels.
E. A smaller than or equal to the distance
.
I
*1 1
the surface of the earth . .
near
moving
projectile
a
of
true
not
‘ ‘
1 '·
‘ ‘ —
9. Which of the followingstatements is
; A‘A·
t A
A
4
*
AIA
resistance?
Ü
against negligible air
'
,_,
·
·
'
A; The horizontal velocity is constant.
4
·
A‘
·
.
J
A
4
·‘ ‘
The vertical acceleration is constant.
‘ < · 4 4
-·
··
time.
to
proportional
directly
is
‘ V ’ '
C. The horizontal displacement
·
._
angle of projection.
‘
' D. The vertical velocity atétny given time is independent of the
1
4
Y
'
A
·
AA
·
-4
The horizontal acceleration is zero.
4
·
A
4
a projectile is doubled, its range "
~ 10. If air resistance is neglected and the initial speed of
IA4
4
4
4
_
A
A; Doubles. J Ü ·
B. Decreases by one-half.
4
’
_
Y
.
'4*”
4
‘
4
.
.
_·
4
4A
4 ‘ 4*
~ C. lncreasesby a factor of four.
4
.
'
-4A
.
4A 4
'
4
4
D. Decreases.by a factor of four.
.
E. Does not change.
^
4
A
4
4**
I
·
4 4Ä
°
true?
is
statements
following
the
of
Which
4 4·
4
A
. ll.AAn object Ais moving to the right at a constant velocity.
4
._
A
144A
”A‘
‘
A
4
A. No forces are acting on the object.
° ° — Y · ~
·
left.
the
to
than
A
right
4
the
to
object
the
on
’
B. A larger numberof forces are acting
'
~
_
_
C. The net force acting Aon the object is to the right.
A
A
A44
E
_
D. No net force is acting on the object.
4
A
1*
A
downward.
E. Just one force is acting on the object, and it is acting
.
W?
4
4 4 4
· PHYS.l43:MECl-IANICS AND THERMAL Pnvsrcs
4
A
44
4
4
4
·
Ä
A
AMANKWAH‘
A.
EXAMINERS: DR. E.M.BA1Deu1a-AADELEYE,. DR. s. ATARAH, DR. HAA. kom&MR.
Y‘
‘
4
-
.
“"‘^
.‘
_:·
4
44
Page 4 of 11
4
~·
CANDIDATE ID NUMBER: |
*4 Pe -4.7).
I
’
|+| '
lll
I
| '
läl
V
-
.
'
I2. 4Two objects with different masses collide and stick to each other. Compared to
before the collision,
°
“
‘
the system of two objgets aßer
collision
has
·
the
A. the same total momentum and the same total kinetic energy.
B. the same total momentum but less total kinetic energy„_
.
C. less total momentum but the same total kinetic energy.
_.
.
..
4
i
D. less total momentum and less total kinetic energy.
4
g
“
E. more total momentum and less total kinetic energy.
I
I
‘
‘
4
\
I
I
| "
13. A box is pushed across a horizontal flat surface with an initial Velocity of
v. It comes to rest after
a displacement d. Assuming that all the kinetic energy of the block is
eventually dissipated by
_ friction, determine the coefficient
of kinetic friction uk if the acceleration due to gravity is g.
_
V
—A
-
eü
· .
4
4
I
=
.
4
B·
; Zi
Mk
.
‘
I
i
[lk —§
vz
D~ ßk —— gg
E
4
'
d2
vz
4
·
4
=
""
‘
.·
.
4
a
g
I
’
· r
.
d
„
·
4
.g
V;
„¤
14. A ball of mass 0.40 kg is initially moving the left at 30 ’m/s towards
a wall. After hitting the wall,
_ 1 . the ballmoves to the right at 20 m s". What
is the impulse of thenet force on the ball during its
P‘
'
[ ·
collision with the wall?
U I
A
4
l
si]
I
_
4
g
-·A. 20 kg m
to the right
5
„
° ·
.I
B. 20 kg m s" to the left
_
_ 44
IC.
-4.0 kg m s" to the right
‘
4 V
4_
D. 4.0 kg m s" to the left .
.
.
.
‘
V
JI4
.
E. 40 kg m s" to the left
l
5i
.
5
15. A constant horizontal force of 20 N is applied tp a 3 kg block
that is initially _at rest on a horizontal
table as shown in Figure 1. The kinetic friction between the
block and table is 10 N. Find the
speedI
I
4
of the block after it has been pushed 3 m.
.-.
‘A.
i6.30ms*1—
5
-C.
D. 3.17 m s‘1
i
g V
i
5-
kg
_
Figure 1
-
··
‘”
°
.
l
· -—
PHYS 143; M1ac11A1~11cs AND THERMALI-Pl-IYSICS
_
1sxAM11~11a1>.s; DR. E. M. BAIDOEÄADELEYE,
DR. s. ATARAH, mz. 1-1. A. KOFFI & MR. A. AMA1~11<wA1-1
-
‘
Page 5 of 11
Y -4
5·
.
4
_16.
_
Ä .
. Ä .1 · _
|__\+\;T|_;_\__\___\___|__|
CANDIDATE ID NUMBER:
in 2 1
the potential energy
WhatAÄis
_m"
AÄ
cm.
9.0
compressed
A
is
A
A
N
A spring with force constant k =;300
.
_
2‘
_
Ä
j
~·
the spring? 2·
A
.
A. 1.2]
B. 2.4J
2.
*
2.
2
1
.
A.Ä
*
A
I
_
.
Ä
2
·
Ä I
Ä
‘*
.
A6Ä
1
c. 27 10:*-JÄ ·
z _
_
{
A
·
'
E
2
·2
2 A
4D. 1.2_><
B. 2.7><Al0"J
2
I
A
5.0 m s", releases a
with a constant velocity of magnitude
vertically
balloonist,_rising
hot-air
17. A
ground. AfterAit is released, the sandbag
1 . Ä Ä sandbag at an instant when the balloon is 40 m above the
A_
height of the sandbag from the ground.A’.
* 1
is in free fall. Determine the maximum
A2
A
1 A. 1.31m
Ä
A
_
I
Ä
I
Ä
B. 41 m
ÄA
AA
C. 39 m
A
D. 48 m
A·
force. The2 pull is at
A
horizontal and frictionless floor by a 90.0 N
18. A 60.0 kg bag is pulled on a flat
the bag whilst
1 Ä
A
the normal force exerted by the floor on
an angle of 30.0° to the floor. Detennine ‘
‘
2_
·
_
A
_
A ‘ I
A
‘
AA AA
A_
A
the pulling forceA acts.1 A
A
A'
Ä
ÄA. 348.1N
1 .
2~
· B. 543.0N
·
_
D. 52.0 N
_
1
A
Ä
2
. ’
1
AA “{Ä
'
1
‘
Ä
of17.0m?
A
·
A1
A_
is pulled such that the bag movesahorizontal
‘
A A'
A A A
AA
.
the bag
19. What is the work done by the force if
A
A
.2
A
_·
B. 688.0N
—
A
·
By 4.60 >< 103]
1.
C. 1.33 >< 103]
‘
2.
AD. 2.40><103}1
A
A 1
E1«11.60><1031
Q
.
A
1 i j
AA
A
”
.A·1A
2
.
A
,
distance
A
22
2
.
2
2.
‘
°‘
1 * =<
A.3.10><103] {A
*
.
1
1
A
c. 402.5 N
1
1
1
2.
ÄÄ
cm. 2
AÄ
the speed ofthe object after it has fallen 75
is released‘ from rest. Calculate
2
.
20. AA.
A 75 g object
1
1
mÄs·‘
2
.
1.7 m·s‘1
Ä
A..
· *1
.
A _
A
_
3.8
B.
'
Ä
_
A1A
A
_
C. 5.1 m s"
; Ä
Ä _ A
1
Ä 1
D. 7.8Äm s·'
Ä
.
2
Ä
E. 9.3 m s"
1
2
_
1
1
'
A
A
AA
_
'
A
·
A
AA
L
AA
A ‘
A ‘
1
‘
PHYS 143: MECHANICS AND THERMAL PHYSICS
H. A. IQOFFI & MR. A. AMANKWAH
ATARAH,
DR.
S.
DR.
E.-MLBAIDOE-AQELEYE,
DR.
EXAMINERS:
Page6of11
J
Ä
·
A
A
2
z
Ä
1
AA
A
I
2Ä
2
.
2
7-
1
—
{/Ä
‘
.
, ·_::··=w£ .
.
Ä
j “ .‘
I
CANDIDATE ID NUMBER: |+|_|_|_1_|I__|;|+| ‘
c. 0.42ms·.‘
A
„
1
.
.
m°‘
A 21. A 50 g. object connected to a spring with force eonstant·k = 1.2 N
is pulled horizonfally to
the left on a frictionless surface. If the spring is stretched 10 cm and released from rest,
calculate
the speed. when the object has travelled 4 cm toward the equilibrium position.
I
B. 0.20 m s·‘
A. 0.11mS·‘
I
I
_
s·‘
D. 0.87 m s·‘
E. 1.50 m
'_
I 22.
10 m
B.C. 7.5.00 mm I
1
i
A. 3.5 m
.
. A
B. 27.8 m 1
ß,
A.B. 11..96X104J
X 104 J
1 A
1
A. 17.4 m .
D; 56..6 m.-
1 l
’
. · E; 110 m
1A
„_
.
A
_.
A
.
„
A
.
‘ 1 · .1‘
24. A 1500 kg car is moving with a speed of 25.0 m s". How much energy
is required to stop the car?
I
‘
_c. 3.6X·104J
.
I
.
AD.4.7X105J
E. 9.4 X 105.1
I
. 1
1 1 BA.c. 3850rradad A
A
1
.
is 2.0 rad s"', find the angle the wheel rotates through in 2.0 s.
A. _l5 rad
.
1.
I
I25.
A wheel is rotating with a constant angular acceleration of 3.50 rad s°2. Ifthe
initial angular
l·
1
23. A stone is thrown horizontally with an initial speed of 8.0 m s" from the edge
of a cliff The time—,
it takes to fall from the top of the cliff to the bottom is 3.4 s. Calculate the
height of the cliff.
I
I
A
D. 8.0 m
I
1
‘
object moves 4.0 m north and then 3.0 m east. Find the magnitude of the displacement.
“
Velocity
’
1
1
A
D. 11 radA
E. 25 rad
I
.26. A 0.30 kg mass, attached to the end of a 0.75 m string,
is whirled around in a horiaontal plane. 1f
A
_
the maximum tension that the string can withstand without
breaking is 250.0 N, determine the
·
A. 22.40 m s°‘
maximum tangential speed.
_
B. 25.00 m s"
A
‘
1
‘
_IAA
c. 19.40 m S4
.
1
D. 32.70 m s"
·
_I1
A E. 275.00 m s·‘
BI
·
\‘wg
.
A
7
A .4
PHYS 143: MECHANICS AND THBRMAL PHYSICS
A
EXAMINERS:
DR. E. M. BAIDOE-ADELEYE, DR. SQATARAI-1; DR. H. A. KOFFI & MR. A.‘
A
AMANKWAH
3
.
Page70f111.
1
{1
.
_.·
. I VI
- _
I
CANDIDATE ID NUMBER: |__\__|?_|__|_|__|__|__| V
V '
.I
s'! while covering 75 m. Find the time
27. A car’s velocity increases uniformly from 5.0 m s"1toV20 m
VVA.
.
. I
taken to cover the distance.
.‘
_
I
10 s
’
YI ‘
B!60s
V
i
·
V c. 2.6 S
D. 3.1 s ·
1
V 3
3
.
I
I
_
E- 2.*7s —
3
{I
g
V
. .
-
N
T
l
‘
i·
'
I
V A V I
V·
~.
.resultant fofce. i ' i '
{W
20.0} N. Calculate the magnitude of the V
A force-(15.01 Iyj 10.0}) N is added to another force
-,,428.
·
AÜÜ.0 N
3
V
i
A
3
°.
{
3”
I1 {B, 23.0N ·
.1
·
.
QV
°E.
Ic.
26.1 N
Ü
3
-1
·
V
D. 32.3N
V
I
·
4x3 where x is inmetres, aets on a particle
29. A position-dependent force in Newton, F (x) = 3xZI +
..
= 4 m. Calculate the work
i iidone byithe‘ __
·
which moves on the x-axis from the origin to the point x
Vi
I
_
V
33.8N
force. ~1
3
.
i ·
V
.
I
. I
.
“’
ei
°
3
1. V’ 1
l
’
A. 1551
.
' {Q
V.Ä
1
Ä
V
V
{
‘‘VV_1.
13. 224{J
3
-
c. 3201
V I
’ ’
V
«
~ D. 3I60J°
Ü
3961
3
3
1
1- ‘ 1
·
V
E
·
1
.-
-.
{Q
r
’
-.’
·3 1 *33
theVangu1ar.
torque of 40 N m. Determine
30. An engine develops a power of 16001r W at Äistant n
Q 3
‘
‘
_3 3 °
3 ‘
.V
·
3
V
i{
- velocity of the engine in revolutions per minute.
”
_
3
’
.
A. 1025 rev min']
.
V
V
B.
V
1780 rev min"
,
V_
”
Vä
Q. 1200 rev min"
D. 1320 rev min"
.
E. 1360 rev min']
I
“ 3
_
l
3
3 .3 “
i
'
' i
V
·
V
·
1
1
-
_ ‘
V
I
V
_
- pays 143: M6cuAN1cs AND THERMAL mvsics
.‘·"
4 .1 {
·
V Ä
.
· 1·
A. AMANKWAH - 1
s. ATARAH, DR. H.-A. 1<o1=m&Nm.
DR.
BAIDOE-ADELEYE,
M.
E3.
EXAMINERS: DR.
.3
3
Page8of11~
I
fi
l·
V
i
V 'Ä
·
_
V
-I
V
i
·
3
Ä
3
A
‘
A
\
·
31. Which of the following statements is true?
An example of athermometric
"‘ property is
I
I. A volume of a gas
- A
·5
A
'
Q
‘
CANDIDATE ID NUMBER: |_|__|_|;|__|_|__|_|
A
· A
A
·
5
·
A,
-
A
Q
I
‘I
5_
5
II. pressure of a confined gas
A
. p
{
IH..electrical resistance of an electrical conductor.
AA.
I and II only
A
F
I and IH only
AB.
A
äö
C. II and III only
‘
, 7
Q
.
D. I,_II, and III
F
y
E; Ionly
..
e
I
'
i
32. Which of the following is not correct?
B/[
F"I.
Real gases obey Boyle’s law at high temperatures and low pressures. X
.
,I
F
II. Ideal gases obey Boyle’s law only at high pressures and·low temperaturesf
A
· .
A .
„
„
_'
III. Real gases obey Boyle’s law under all conditions. {I ‘
‘
_ ' A. Iand II only 5
Q
fA
A
B. I and IH only
C. II and III only
AI
'
_
·
5
_
D. I, II and III
A
5
{E.
I only
5 ·A 33. Which of the following statements is true? A
U?
g
·
Q
·
A e.AA
_
’I
In an
_
isobaric expansion of a gas,
\1
work done by the gas is independent of its pressure.
A
AT'
5
5
II work done by the gas is proportional to the change in its volume. / ‘
_A
III work is done by the gas at the expense of its intemal energy. A F
A
AA
·
‘
5
F
A.
I
only
A
A·
‘
5 B. II only
5-_
A Q
_
g
Q
F
F
Q
C. III only
ß I and II only'
E. I and III only A
I
A
·
·
”
.
Q;
34. The first law of thermodynamics is most closely related to 5A
_
_
Q
”
5
A. the definition of the. absolute zero.
A
A-B.
the definition of an ideal gas.
-_
ßI
‘
C. theconservation of energy.
‘
_
5 .
D. thermal expansion.
_
F
E. the conservation of momentum.
l
A
Q
F
Q
..
is added to the gas in one cycle?
A. 2W
B. W
C. % W
I
{
‘\
I{.
«
\
p
Fgf
I
D. 0
E. — W
5
5
*5
I.
5'
U
‘
‘
U
.
·
Q
Q IF
.’
.
A
·
F
_
A
”
·
F
p F · 35. Anideal gas undergoes a cyclic process in which total work Wis done by the gas. What total heat
Q
.
ääi
Z
A R1-ws 143. M6cHAN1cs AND THERMAL Ruvsics
EXAMINERS:·DR. E. M. BAIDOE-ADELEYE, DR. s. ATARA1-1, DRA.·1-1. A. korri & MR;FA. AMANRWA1-1
QQ
‘
A
A
Page 9 of 1_1
F
'
_
..
9
4
.
.- 4
·V 4. ·4
4 44 4 4 4 4 M
444
i
€1’l€I'gy.
A. 116 J
·
.
4V
4
13. 320 J
4
C. 575 J
4
4
4
‘
4
D. 640 J
4V 9:13. 0J
V.
A. as Q.
4
‘
4
.
4
{
l‘
4
V
.
4
7 9 Iy"
‘
4
-4
m3 and temperature of 20 °C to
‘
adiabatiC4¢0¤Stant of air 4
S/Phi
·--
~
___
2
,2
4 V
.
·
9
24 i CM
”‘
9
° . . 4- ·
V-
.
V
93 {
V4
.
\i°’4
9
'
4
44
I9
4
·V
’
{is
at 620 K takes _in 550 J of‘beatVat this
reservoir
high-temperature
whose
engine
Carnot
39.A
thetbemial
the low·temperature reservoir. What is
i
temperature in each cycle and gives up 335 J to
V'
V
- .
*
efficiency of the cycle?
n
.
4
.
.
V
4 .4413. 300K”
9 '9
I
V
.4
·
isy=1.4.)‘
125K
D. 275K 4
4
4
-
”
final temperature of the gas.
twice its original volume. Calculate the
—\
Ä9A.
_
V
·{ @226K
· . 298 K
V
V *
44 4
9.
E. is zero.
4
‘T
V
-
from an initial volume of 2
38. A quantity of air expands adiabatically
4
V
9
4
4
·i
° .
-
work done by the engine
from a hot reservoir.4 The amount of
9
must be greater than Q.
” B.
C. must be less than Q.
D. could be greater than Q. 4
j
9
4
4
37. A heat engine absorbs heat
.
9
m3 undergoes a quasiÄ
250 kPa and a volume of 4.5
of
apressure
°C,
100
at
initially
An ideal gas
'36.
change in the internal
pressure is reduced to 150 kP4a. Find the
static, 4isothermal expansion until its
V
4
44 44
4
·
4
.
.
4
' ii ' ”
‘ I V,
CANDIDATE ID NUMBER:
‘
I
4i 9
{
V
4
-4
V .A.60.9%
9
>9·
2V.4
V ..
{
{
.
4
9
.
4
. .
4
44
4
4
{
9 9
9 ·
C. 29.T’%’4
K
D. 70.9%
{
V
94
4
4
E. 1.9.1 %
4
atm.9
pressure4of 1
an ideal gas at a temperature of 0 °C and a
‘
9
40. Calculate the volume of two moles of
‘
'4
V
99 9 ‘A.1.1><10·2m3 V
’
.
m3
9V
9
.4
4
·
m3
4 4 E. 9.4 ><10’2
‘
4 =
9
-2.3 210-2
9~ 4
4.5 210-2 m3 -
. 7.7 ><10·2m3
4
4. PHXS 143: MECHANICS AND THERMAI. PHYSICS
_
.4
.
4
*4
..
_
{
DR. H. A.4KOF4FI & MR. A._AMANKWAl-1
EXAMINERS: DR. E. M. BAIDOE-ADELEYE, DR. S. ATARAH,
Page
4
4
.
Y
4i i
‘
U
li
l i
9 [
104of11
4
”
.
·.2;4
\1
.1/
.
?5
1
1
1
-
-11
1
1
\\
1
CANDIDATE ID NUMBER: |_|_|_|_|_|_|_|_|
‘
_
V
41. Thetemperature of an ideal gas initially at 47 °C changes
such that its pressure is doubled and its
volume reduces to two-thirds of its origina11value. Calculate_the
new temperature of the gas.
1
1
|
·
I
A. 153.67 °C
B. 217.76 °C
c. 374.76 ec
OC
5
1
1
1
·
B. 591.67 CTC
D. 462.67
1
1
1
.
42. An ideal gas sample has a pressure of 2.5 atm and a
volume of 1.0 m3 at a temperature of 30 °C.
Determine the number of moles of gas in the sample.
1
1
1
1 A. 9.9 X_10“‘ 1
I
1
· 1 · A. 1.05_>él05J 1
B.
‘
1 c. 11.0X1_0·2»
10.1 ‘15
D. l01·
I
· 1 1
‘
11
·
1
_ 1
B. 250
1
.
5
_
.
11
V1
1 · 43. How much heat is required to change 0.50 kg of ice 1at 01 °C to water
at 50 °C?
1
1
D. 4.38 X 1051
1B. 1.13X11051
l1
1
.
15 15
1
1
1 1
1
5
1 .
_
1
15
1
1
B. 1.67 X 105 1 1
1
1c.
_
1
2.71 X _105
I
'
1
.
7 1 15
f
1
1
,
1
44. To raise the temperature of a 2.00 kg piece ofmetal from
20 °C to 100 °C, 61.8 kJ ofheat is added. 1
.1What is the specific heat of theq?11/etal? 1
K‘1‘
1
1 ·
.
·11
V
I
A. 0.390 kJ kg'
1B. 0.310 kJ kg" K1'
I
1 c. 1.65k1kg·1.K·‘
1 ‘ D. 1.24 kJ kg" K1'
1<·‘
B. 0.770 kJ kg'
I
1
1
1 · 1
1 1
1
1
. 1
.
1
1
545.
A refrigerator extracts 25.0 kJ from a cold reservoir
and rejects
the coefficient of performance of this refrigerator?
I
5
,.1 ä5
1 1 11
5J
1
1
A. 2.5
5
35.0 kJ to a hot reservoir. What is
11
5
1 1
1é
1
1
1f
5 B. 3.5
1
.
1
1I
-1
C. 1.4
1
.D.
5.0I
1
E. 4.0
5
5
1.
1
1
/
II
1
.1
·
’
5
PHYS 143: MECHANICS AND THERMALPHYSICS
5
EXAMINERS: DR. E. M. BAIDOE-ADELEYE, DR. S.
ATARAH, DR. H. A. KOF1§l & MR. AI AMANKWAH
1
1
Page 11 of11
11 „
1
"‘
1
1
V