How Things Works (PHYS1055)
Assignment 1
Due Date: 5:00p.m., February 20, 2017
The number in the square bracket is the word limit in your answers. Each question carries 20 marks.
1. There is a product called 55 degree cup, as shown in the figure. When you
How Things Works (PHYS1055)
Assignment 2
Due Date: 5:00p.m., March 31, 2017
The number in the square bracket is the word limit in your answers. Each question carries 20 marks.
1. During winter seasons, farmers usually spray their plants (or fruits) with w
How Things Works (PHYS1055)
Solutions to Assignment 1
1. The cooling substance inside the cup is a mixture of chemical salt which has a melting point
of 55oC. The main ingredient in the mixture is sodium acetate trihydrate. When heat flows from
the hot wa
Chapter 7 Rotation of Rigid
Body
Rigid Object
We can model the motion of an extended object
by modeling it as a system of many particles.
The analysis is simplified if the object is a
rigid object.
A rigid object is one that is nondeformable.
The relat
Chapter 2
Kinematics: Motion of a Particle in
One and Two Dimensions
Kinematics
Describes
motion while ignoring the
external agents that might have
caused or modified the motion
Motion represents a continual change
in an objects position.
Types of Motion
Chapter 6
Linear Momentum, Collision &
Center of Mass
Linear Momentum
The linear momentum of a particle or an object that can be
modeled as a particle having mass m moving with velocity
v is defined to be the product of the mass and velocity:
p mv
The ter
Chapter 3
Force, Newtons Laws of Motion
Newtonian Mechanics is based on the laws
presented by Isaac Newton (16421727).
However,
at very large speeds (an appreciable fraction of the
speed of light c), Newtonian mechanics must be
replaced by Einsteins spec
Chapter 8
Simple Harmonic Motion (SHM)
8.1 Equation of Motion
A vibrating system for which the restoring force is directly
proportional to the negative of the displacement ( F kx ) is said
to exhibit Simple Harmonic Motion (SHM), and the system is
referre
Chapter 4
Circular and Curvilinear Motions
Here we consider particles moving not along a straight line
the curvilinear motion. We first study the circular motion, a
special case of curvilinear motion. Examples we have already
studied earlier are the proj
PHYS1050 Physics for Engineering Students
Time allowed: 1 hour
Name:
Test 2
University No.:
November 30, 2015
Class:
A/B
Section A (56%)
Multiple Choice Questions (There is only one answer for each question. Circle the correct answer
with ball pen. Each q
PHYs1050 PhV$:C$for EngIneer
Tes 1,(23rd Oct
N
n s udents
)
u jv /sjfE/No
:
:
+(rJ+2
=(/r
2
2)
AcGeleration in plane polar and nomaltang9ntial GoOrdinates
Free Fa1l AGceleratiOn
0)
:=

^
t
;
g=9.811n/s2
p eC oice ques oIls(Ske Ch your work n s o Just f
PHYS1050 Physics for Engineering Students
Instructors:
Prof. K. S. Cheng
Email: hrspksc@hku.hk
Office: Rm 530, Chong Yuet Ming Physics Building
Dr. M.K. Yip
Email: mankit@hku.hk
Office: Rm 415B, Chong Yuet Ming Physics Building
Contents
8 chapters in Mec
Engineering for Sustainable Development
ATMOSPHERE AND AIR POLLUTION
PROGRESS & OUTCOMES
Atmospheric Environment
Protect us from hostile environment
Absorbs cosmic rays & (some)
meteorites
Allow sun radiation only in the
range of 3002500 nm for
photosy
ENGG1205
Introduction to
Mechanical Engineering
(Fluid Mechanics)
Prof. C.O. Ng
Department of Mechanical Engineering
HW 71, Email: cong@hku.hk
Fluid? Fluid Mechanics?
Concept of a Fluid
How to distinguish fluid from solid?
Fluid is a substance that defo
Chapter 1 Review of Multivariable Calculus
1
11
Review of Multivariable Calculus
In the study of introductory level physics, we often deal with single variable functions.
For example, the variation of the speed of a onedimensional harmonic oscillator wi
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Solutions to Exercise 1
1. (a) The function sin1 (x2 + y 2 2) is defined only when 1 x2 + y 2 2 1
since 1 sin z 1 for any z. So the domain of f is all points (x, y) satisfying
1 x2 + y 2 3. The range of f is
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Solutions to Exercise 1
1. (a) The function sin 1 (x2 + y 2 2) is defined only when 1 x2 + y 2 2 1
since 1 sin z 1 for any z. So the domain of f is all points (x, y) satisfying
1 x2 + y 2 3. The range of f i
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Exercise 3
1. Evaluate the line integrals along the curve C.
Z
(a)
(1 + xy 2 ) ds, C : ~r(t) = (1 t) i + 2(1 t) j, 0 t 1
C
Z
1
(b)
ds, C : ~r(t) = t i + 32 t3/2 j, 0 t 3
1+x
C
Z
(c)
(3x y) ds, C consists of
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Exercise 2
1. Match each vector function with its graph (labeled (I)(IV). Give reasons for your
choices.
(a) F~ (t) = (t t2 ) i + (t3 t) j
(b) F~ (t) = (t + sin 5t) i + (t2 + cos 6t) j,
(d) F~ (t) = cos 3t
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Exercise 1
1. Describe the range and domain of each of the following functions.
(a) f (x, y) = sin1 (x2 + y 2 2)
ln(y x)
(b) f (x, y) = p
4 x2 y 2
(c) f (x, y, z) = x + y z + xeyz
exyz
(d) f (x, y, z) =
xyz
only depends on physical
quantities
charge independence
current back to battery, charging
generate exact and opposite internal Efield
Torque = p x E
align but not perfectly
Alignment of electric dipole downwards
=> more positive
not a good conductor but g
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Homework 1
(Due date: 10 Feb 2017, 12:30 pm)
1. (a) Find the indicated limit if it exists. If the limit does not exist, explain why.
2xy 3
(i)
lim
(x,y)(0,0) x2 + 8y 6
xy+2 x2 y
(ii)
lim
(x,y)(0,0),x6=y
x y
PHYS1316/PHYS2155 Methods in Physics II
2016/17 Homework 2
(Due date: 24 Feb 2017, 12:30 pm)
1. (a) Given that the directional derivative of the scalar field (x, y, z) at the point
is 5 and that k(3, 2, 1)k = 5,
(3, 2, 1) in the direction of ~u = 2 i j 2
PHYS 2255 Introductory Electricity and Magnetism (2017 Spring)
HOMEWORK 1 Suggested Solutions
1. Solution:
A B
(a) From cos , we get
 A  B 
, so
(b) Since the vector on yaxis is ay ,
, so
Since the vector on z axis is
(c)
So the unit vector i
PHYS2255 Introductory Electricity & Magnetism
HOMEWORK 1
DUE DATE: February 7, 2017 (Tuesday) 3:00pm
Please notice that only a subset of the questions in the homework submitted will be
graded and counted for Assignment marks.
All assignments must be retur
PHYS2255 Introductory Electricity & Magnetism
HOMEWORK 2
DUE DATE: February 17, 2017 (Friday) 3:00pm
Please notice that only a subset of the questions in the homework submitted will be graded
and counted for Assignment marks.
All assignments must be retur
PHYS 2255 Introduction to Electricity and Magnetism Spring 2017
Tutorial 2 (Week of 2017 Feb 20  24)
1. Consider a cube with each side of length a, with one of the corner of
the cube at the origin and three sides lying on the x, y, and z axes
respectivel
PHYS2255 Introductory Electricity and Magnetism (2017 Spring)
HOMEWORK 2 Suggested Solutions
1. (a) In cylindrical coordinates,
dl drr rd dzz
For the loop C,
(i)
r = A,
/3
For
2
/ , and r = A
2
(ii)
3 cos 2 /3
For
4
, and r = A
93
4
3r cos 2 /3
(b) For t
Rice is Life!
http:/www.youtube.com/watch?v=I72xRyqRfqo
True? What do you think?
Rice is Life  Rice Facts
Staple food for half of world's population cultivated in 113 countries
Provides 27% of dietary energy supply and
20 percent of dietary protein int
The Economist
Feeding 1.36 billion people
Daily bread
As China globalises, some still
think it should be selfsufficient in food
Oct 26th 2013  BEIJING  From the print edition
SELFRELIANCE is a notion now more closely associated with the
juche doctrine