Download Final Exam - Kuniv.edu.kw

Physics Department
Physics 101
Final Exam
Summer 2010
Sunday, August 8, 2010
2:00 p.m. – 4:00 p.m.
Student’s Name: ……...…………………………….…………………………………….…………
Student’s Number: ….………………………………………………………………………………
Choose your Instructor’s Name:
Dr. Adnan Al-Yaseen
Dr. Abdul-Mohsen Ali
Dr. Tareq Alrefae
Dr. Abdulnasser Burezq
Dr. Fatma Al-Dossari
Dr. Ashraf Zaher
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
P16
P17
P18
P19
P20
Points
Points
Total
Important:
1.
Answer all questions and problems.
2.
Each question/problem will be assigned 1 point.
3.
No solution = no points.
4.
Check the correct answer for each question/problem.
5.
Assume g = 10 m/s2.
6.
Mobiles and pagers are not allowed during the exam.
7.
Programmable calculators, which can store equations, are not allowed.
GOOD LUCK *
Kuwait University – Science College – Physics dept. – PHYS 101
Summer 2010 (08/08/10)
1. The cross product of vector A with itself ( A × A ) is:
(a)
(b)
(c)
(d)
(e)
A2
2A
A
Zero
1
2. A disk is rotating in the clockwise direction as shown with an angular velocity ω and an angular
acceleration α. Which of the following statements is correct?
(a) ω and α are the same for all points on the disk.
(b) ω is the same for all points on the disk, but α is different for
each point.
(c) α is the same for all points on the disk, but ω is different for
each point.
(d) ω and α are both different for each point on the disk.
(e) None of the above.
3. A disk is rotating in the clockwise direction about an axis
that goes through its center. Points a and b have linear
velocities va and vb respectively. Which of the following
statements is correct?
(a)
(b)
(c)
(d)
(e)
a
b
va > vb
va = vb
va < vb
va = 0
vb = 0
4. The shown ring and solid disk have the same mass and radius. Which of the following is correct
about their moments of inertia ( Iring and Isolid )?
(a)
(b)
(c)
(d)
(e)
Iring > Isolid
Iring < Isolid
Iring = Isolid
Iring = Isolid = 0
Iring = 2 Isolid
5. A cylinder is rotating counter-clockwise as shown in
the figure. If the angular velocity ω is decreasing
uniformly, then the angular acceleration vector α
points in the
(a)
(b)
(c)
(d)
(e)
+ z direction
– z direction
+ y direction
– y direction
– x direction
2/5
Kuwait University – Science College – Physics dept. – PHYS 101
Summer 2010 (08/08/10)
6. For the completely inelastic collision shown, what can be said about the kinetic energy (KE) of the
system before and after collision?
(a)
(b)
(c)
(d)
(e)
KEbefore = KEafter
KEbefore > KEafter
KEbefore < KEafter
KEbefore = KEafter = 0
KEbefore + KEafter = 0
7. A block of mass m is pulled at a constant velocity along a rough horizontal surface by an applied
force F. If the coefficient of friction is μ, then the frictional force is:
(a)
(b)
(c)
(d)
(e)
μmg
μ(mg + F sin θ)
μ(mg – F sin θ)
μ(mg + F cos θ)
μ(mg – F cos θ)
F
θ
m
8. A bullet of mass m is fired into a block of wood of mass M, that is suspended like a pendulum
and makes a completely inelastic collusion with it. The block swings up to a maximum height of
h. The initial speed of the bullet (v) is:
(a) m  M
(b)
(c)
(d)
(e)
2 gh
m
mM
2 gh
M
M
2 gh
m
m
2 gh
M
2m
2 gh
M
m
v
M
h
9. A ball of mass 0.4 kg is thrown horizontally to the left against a wall as shown. It hits the wall
with a speed of 30 m/s and rebounds horizontally to the right with a speed of 20 m/s. The
impulse (in N.s) of the net force on the ball during its collision with the wall is:
(a)
(b)
(c)
(d)
(e)
20 to the right
20 to the left
4 to the right
4 to the left
Zero
10. A stone is released from a balloon that is descending at a constant speed of 10 m/s. Neglecting air
resistance, after 20 seconds the speed of the stone is:
(a)
(b)
(c)
(d)
(e)
10 m/s
100 m/s
190 m/s
200 m/s
210 m/s
3/5
Kuwait University – Science College – Physics dept. – PHYS 101
Summer 2010 (08/08/10)
11. A light cable is wrapped around a solid cylinder. The cylinder (mass
M, radius R, and moment of inertia ½ MR2) rotates without friction
about a horizontal axis. A block of mass m that is attached to the cable
is released from rest and is left to fall a distance h. The speed (v) of the
block as it hits the ground is:
(a)
(b)
(c)
(d)
(e)
2 gh
M 

1 

2
m

mgh
2M
2 gh
2m 

1

M 

Mgh
m
mgh
M
M
R
m
h
12. A wheel rotates with a constant angular acceleration of 2.25 rad/s2. After 4.0 seconds it has
rotated through an angle of 60 radians. The initial angular velocity of the wheel (in rad/s) is:
(a)
(b)
(c)
(d)
(e)
Zero
9.0
10.5
15
-19.5
13. A projectile is fired over level ground with an initial velocity that has a vertical component of 20
m/s and a horizontal component of 30 m/s. The distance from launching to landing points is:
(a)
(b)
(c)
(d)
(e)
40 m
60 m
80 m
120 m
180 m
14. A 5.0 kg cart is moving horizontally at 10.0 m/s. In order to change its speed to 6.0 m/s the net
work done on the cart must be:
(a)
(b)
(c)
(d)
(e)
-160 J
-90 J
90 J
160 J
340 J
15. A force of 10 N holds an ideal spring with a 20 N/m spring constant in compression. The
potential energy stored in the spring is:
(a)
(b)
(c)
(d)
(e)
0.5 J
2.5 J
5J
10 J
200 J
4/5
Kuwait University – Science College – Physics dept. – PHYS 101
Summer 2010 (08/08/10)
16. A billiard ball ‘A’ moving at 5 m/s strikes a
stationary ball ‘B’ of the same mass. After the
collision ball A moves at 4 m/s at an angle of 37
with respect to the original line of motion.
Assuming an elastic collision, the magnitude of the
final velocity vbf (in m/s) of ball B is:
(a)
(b)
(c)
(d)
(e)
3
6
9
12
Zero
17. Block A, with a mass of 4 kg, is stationary while block B, with a mass of 8 kg, is moving at 3 m/s.
the center of mass of the two block system has a speed in m/s of:
(a)
(b)
(c)
(d)
(e)
Zero
1.5
2
3
12
18. A small object of m, on the end of a light cord, is held horizontally at a distance r from a fixed
support as shown. The object is then released. What is the tension in the cord when the object is
at the lowest point of its swing?
(a)
(b)
(c)
(d)
(e)
mg/2
mg
2mg
3mg
mgr
r
m
19. If a wheel is turning at a constant angular velocity of 3.0 rad/s, the time it takes to complete one
revolution is approximately:
(a)
(b)
(c)
(d)
(e)
0.33 s
0.67 s
1.0 s
1.3 s
2.1 s
20. Four identical particles, each with mass m, are arranged in the x, y
plane as shown. They are connected by light sticks to form a rigid
body. If m = 2.0 kg and a = 0.5 m, the moment of inertia of this
system about the y axis is:
(a)
(b)
(c)
(d)
(e)
2.0 kg.m2
3.0 kg.m2
4.0 kg.m2
6.0 kg.m2
9.0 kg.m2
y
a
a
a
x
a
5/5