Physics Department
Physics 101
Final Exam
Spring Semester
Sunday, May12, 2013
Model
Answer
02:00 p.m. – 04:00 p.m.
Student’s Name: ………………..………………….…………………………………….…………
Student’s Number: ….……………………………………
Section: ……………………
Choose your Instructor’s Name:
Prof. Fikry El-Akkad
Dr. Ahmed Al-Jassar
Dr. Hassan Ra’fat
Dr. Abdul-Mohsen Ali
Dr. Hassan Manaa
Dr. Ashraf Zaher
Dr. Tarek Ramadan
Dr. YacoubMakdesi
Dr. Adnan Al-Yaseen
Dr. Hala Al- Jassar
Dr. TareqAlrefai
Dr. Fatema Al-Dousari
Dr. Nasser Demir
Grades:
#
Pts
Q1
Q2
Q3
Q4
Q5
SP1
SP2
SP3
SP4
SP5
LP1
LP2
LP3
LP4
LP5
Total
1
1
1
1
1
2
2
2
2
2
5
6
6
5
3
40
Important:
1.
2.
3.
4.
5.
6.
7.
8.
Answer all questions and problems.
Full mark = 30 points, arranged as follows:
i. 5Questions
ii. 5Short Problems
iii. 5Long Problems.
No solution = no points.
Use SI units.
Check the correct answer for each question.
Assume g = 10 m/s2.
Mobiles and pagers are not allowed during the exam.
Programmable calculators, which can store equations, are not allowed.
GOOD LUCK
Part I:Questions (Choose the correct answer, one point each)
Final Exam – PHYS101
Spring 2012-2013
Q1. A block of mass m is dropped onto a vertical spring of constant k. If the block reaches the spring
with a velocity v, then the net work done by all forces during the maximum compression x is:
a. – ½ kx2
v
b.a. –2 mgx
c. – mgx
x
d. – ½ mv2
e. – ½ mgx
Q2.
A roller coaster moveson the smooth track as shown in the figure. The radius R A = 2 R B .
If the speeds at A & B are adjusted to keep the roller coaster just in contact with the track (N=0),
then V A at A is related to V B at B as:
a. VA = VB
b. VA = 2 VB
c. V = V B
A
2
d. VA = 2VB
e. V = VB
A
2
A
B
RA
RB
UO
Q3. Bader is standing on the floor of a cart that is moving horizontally at a constant speed (Ignore air
resistance). He jumps straight up relative to the coordinate system of the moving cart. You may
assume that his feet and other body parts move rigidly together. Near which point will he land
on the cart floor?
a.
b.
c.
d.
e.
A
B
C
D
E
is constant as in projectiles
B
C
D
V
A
E
Q4. m 1 & m 2 are two equal masses. m 1 moves with speed v toward a stationary mass m 2 .
The maximum energy transferred to m 2 occurs if the collision is:
a. one dimensional inelastic collision
b. perfectly inelastic collision
c. two dimensional inelastic collision
Inelastic collision (loss of energy)
Two dimensional elastic collision
(share of energy)
d. one dimensional elastic collision
e. two dimensional elastic collision with equal angles
Q5. A & B are two sprockets connected by a belt that does not slip and runs with constant linear
speed v. If r A = 4 r B ,then the relation between their angular velocities ω A &ω B is:
v
a. ω A = ω B
b. ω A = 2ω B
v
c. ω A = 4ω B
d. ω A = ½ ω B
e. ω A = ¼ ω B
rB
rA
Part II: Short Problems (2 points each)
2
Final Exam – PHYS101
Spring 2012-2013
SP1. A block of mass 5 kg slides across a rough surface with µ k = 0.6. It collideswith a spring of
constant 1000 N/m as shown in the figure A. It compresses the spring by 40 cm (figure B) and
then returns back to its original position (figure C). Find the change in kinetic energy (in J) of
the block between A and C.
A
B
C
J
x=0
SP2. A system of three uniform rods of lengths L, 2L and 3L are attached as shown in the figure.
If L = 4.0 m,find the coordinates (x cm &y cm ) of the center of mass (in m) relative to the
point O.
y
3L
L
O
SP3. A particle of mass 8 kg rests on a smooth table. It is acted on by two forces
x
2L
&
. (Note: x
and y are in a plane parallel to the surface of the table)The particle moves with constant
acceleration of 2.0 m/s2 in the positive x direction.
Find
is 12.0 N (in the positive y- direction).
(in N). (in unit vector notation)
y
N
m
N
N
x
m
F2x
F2y
3
Final Exam – PHYS101
Spring 2012-2013
SP4. m 1 & m 2 are two equal masses. m 2 is stationary and m 1 runs toward it with a speed of 50 m/s.
After two dimensional elastic collision it is found that m 2 will move with a speed of 30 m/s at an
.Find the velocity (in m/s), in magnitude & direction of m 1 after this elastic
collision.
v1 = ?
(equal masses)
m1
m1
m2
v2= 30 m/s
8 kg
SP5. The four masses shown in figure are connected by
12 kg
r
r
massless rods and rotates horizontally about the center
point O with constant angular velocity of 2 rad/s.
r
Find the total rotational kinetic energy (in J).
12 m
O
r
16 m
12 kg
8 kg
J
Part III: Long Problems (Points for every problem are listed on the cover page)
LP1. m 1 is released from rest in the system shown in
the figure. The disk P has moment of inertia of 0.36 kg m2
f
P
and its radius is 0.6 m.If frictional tangential force of the
disk is 5N,find the acceleration of m 1 (in m/s2)
m1
8.0 kg
4.0 m
m2 2.0 kg
f
T1
T1
T2
T2
disk
m1 g
m1
m2 g
m2
4
Final Exam – PHYS101
Spring 2012-2013
LP2. In the figure shown, the left track is smooth. m 1 (8 kg) is released from rest from a height of 5m.
It collides and stick with a stationary mass m 2 (12 kg). Both masses move together by a distance of
2 m on a rough horizontal surfaceuntil they stop. Find:
m1 = 8 kg
a. The coefficient of kinetic friction of therough surface.
b. The loss in kinetic energy(in J) during collision.
m2 = 12 kg
5m
smooth
surface
a)
b)
rough
surface
J
LP3. During construction of a very high tower a hammerhead with mass of 200 kg is dropped from
height of 5 m above the top of I-beam being driven into the ground. Accordingly the I-beam is
driven 18 cm into the ground. The vertical rail that guides the hammerhead exerts a constant
frictional force of 380 N on the hammerhead.Find:
a. Velocity (in m/s) of the hammerhead just before it collides with the I-beam.
b. The average force (in N) the hammerhead exerts on the I-beam. (neglect air resistance)
a)
Hammer
head
guide
rail
n
5m
f
I
beam
mg
b)
ground
= 4.66 ×104 N
LP 4. A homogenous rod of mass (m) of0.5 kg and length (l) of 30 cm is pivoted from one end at point
O and is kept horizontally (pivot is frictionless). It is then releasedformthe rest.Find:
a. The moment of inertia (in kgm2) of the rod about O. (I cm =
m l2 )
b. The linear speed (in m/s) of the free end (a) as it passes the
O
mg
l/2
vertical position.
= 0.015 kg m2
a)
a
b)
rad/s
5
a
Final Exam – PHYS101
Spring 2012-2013
LP5. Felix rises up in a huge balloon from the ground
(Level A) with constant speed of 5 m/s. Arriving at
height of 39 km (Level B), then he releases himself
in space (as free fall) and descends in air by total
distance of 36500 m (Level C).
(New record)
39000 m
LEVEL - B
The measured
velocity at C is 373 m/s. He then opens the
parachute and continues his way to the ground
(Level A).
Calculate the work done by air
resistance during the 36500 m falling distance
from Level B to Level C. His total mass including
the parachute is 100 kg.
36500 m
(260 s)
= 2.95×107
~ 3×107 J
5 m/s
LEVEL - C
V = 373 m/s
LEVEL - A
Balloon launches,
carrying Felix in the
capsule.
Return to
LEVEL - A
2500 m
280 s
On October 14th 2012, An Australian athlete
(Felix Baumgartner) has record to be the first
man breakup speed of sound. His velocity at
level C is 373 m/s (velocity of sound is 340 m/s)
This incredible event is summarized in the
following problem (with some simplifications)
6