THOSE WHO OBTAINED PASS MARKS….
GOOD LUCK NEXT TIME!!
THOSE FAILED TO OBTAIN PASS MARKS.
Multiple choice questions – 20 marks
Theory and application – 80 marks.
Topics included in semester exam.
kinemetics – Speed , velocity , distance and acceleration
– Graphical analysis of motion ( speed time graph and distance time graph)
Dynamics – Force, weight, newton’s laws of motion, turning effect of forces, momentum and pressure ( solid, lquid, hydraulics)
Electricity and magnetism
Energy and power.
1. position or displacement which tells us exactly where the object is,
2. speed or velocity which tells us exactly how fast the object’s position is changing or more
familiarly, how fast the object is moving, and
3. acceleration which tells us exactly how fast the object’s velocity is changing.
You will also learn how to use position, displacement, speed, velocity and acceleration to describe
the motion of simple objects. You will learn how to read and draw graphs that summarise the
motion of a moving object. You will also learn about the equations that can be used to describe
motion and how to apply these equations to objects moving in one dimension.
Definition: Displacement
Displacement is the change in an object’s position. The displacement of an object is defined as its change in position (final position minus initial position). Displacement has a magnitude and direction and is therefore a vector. For example, if the initial position of a car is xi and it moves to a final position of xf , then the displacement is:
xf − xi
However, subtracting an initial quantity from a final quantity happens often in Physics, so we
use the shortcut ∆ to mean final – initial. Therefore, displacement can be written:
∆x = xf − xi
Important: The symbol ∆ is read out as delta. ∆ is a letter of the Greek alphabet and is
used in Mathematics and Science to indicate a change in a certain quantity, or a final value
minus an initial value. For example, ∆x means change in x while ∆t means change in t.
Important: The words initial and final will be used very often in Physics. Initial will always
refer to something that happened earlier in time and final will always refer to something
that happened later in time. It will often happen that the final value is smaller than the
initial value, such that the difference is negative. This is ok!
Definition: Vectors and Scalars
A vector is a physical quantity with magnitude (size) and direction. A scalar is a physical
quantity with magnitude (size) only.
The differences between distance and displacement can be summarised as:
Distance
1. depends on the path
2. always positive
3. is a scalar
Displacement
1. independent of path taken
2. can be positive or negative
3. is a vector
Definition: Velocity
Velocity is the rate of change of position.
Definition: Instantaneous velocity
Instantaneous velocity is the velocity of an accelerating body at a specific instant in time.
Definition: Average velocity
Average velocity is the total displacement of a body over a time interval.
Velocity is the rate of change of position. It tells us how much an object’s position changes in
time. This is the same as the displacement divided by the time taken. Since displacement is a
vector and time taken is a scalar, velocity is also a vector. We use the symbol v for velocity. If
we have a displacement of ∆x and a time taken of ∆t, v is then defined as:
velocity (in m · s−1 ) =
v = change in displacement (in m) / change in time (in s) or = ∆x / ∆t
Velocity can be positive or negative. Positive values of velocity mean that the object is moving
away from the reference point or origin and negative values mean that the object is moving
towards the reference point or origin.
Important: An instant in time is different from the time taken or the time interval. It
is therefore useful to use the symbol t for an instant in time (for example during the 4th
second) and the symbol ∆t for the time taken (for example during the first 5 seconds of
the motion).
Average velocity (symbol v) is the displacement for the whole motion divided by the time taken
for the whole motion. Instantaneous velocity is the velocity at a specific instant in time.
(Average) Speed (symbol s) is the distance travelled (d) divided by the time taken (∆t) for
the journey. Distance and time are scalars and therefore speed will also be a scalar. Speed is
calculated as follows:
speed (in m · s−1 ) = distance (in m) / time (in s) or = d / ∆t
Instantaneous speed is the magnitude of instantaneous velocity. It has the same value, but no
direction.
Differences between Speed and Velocity
The differences between speed and velocity can be summarised as:
Speed
1. depends on the path taken
2. always positive
3. is a scalar
4. no dependence on direction and
so is only positive
Velocity
1. independent of path taken
2. can be positive or negative
3. is a vector
4. direction can be guessed from the sign (i.e. positive or negative)
Additionally, an object that makes a round trip, i.e. travels away from its starting point and then
returns to the same point has zero velocity but travels a non-zero speed.
Definition: Acceleration
Acceleration is the rate of change of velocity.
Acceleration (symbol a) is the rate of change of velocity. It is a measure of how fast the velocity
of an object changes in time. If we have a change in velocity (∆v) over a time interval (∆t),
then the acceleration (a) is defined as:
acceleration (in m · s−2 ) = change in velocity (in m · s−1 ) / change in time (in s)
a= ∆v / ∆t
Since velocity is a vector, acceleration is also a vector. Acceleration does not provide any infor-
mation about a motion, but only about how the motion changes. It is not possible to tell how
fast an object is moving or in which direction from the acceleration.
Like velocity, acceleration can be negative or positive. We see that when the sign of the acceler-
ation and the velocity are the same, the object is speeding up. If both velocity and acceleration
are positive, the object is speeding up in a positive direction. If both velocity and acceleration
are negative, the object is speeding up in a negative direction. If velocity is positive and accel-
eration is negative, then the object is slowing down. Similarly, if the velocity is negative and the
acceleration is positive the object is slowing down.
Important: Acceleration does not tell us about the direction of the motion. Acceleration
only tells us how the velocity changes.
Important: Deceleration
Avoid the use of the word deceleration to refer to a negative acceleration. This word usually
means slowing down and it is possible for an object to slow down with both a positive and
negative acceleration, because the sign of the velocity of the object must also be taken into
account to determine whether the body is slowing down or not.
Definition: Physical Quantity A physical quantity is anything that you can measure. For example, length, temperature, distance and time are physical quantities.
SI Units We will be using the SI units in this course. SI units are the internationally agreed upon units. Historically these units are based on the metric system which was developed in France at the time of the French Revolution.
Definition: SI Units The name SI units comes from the French Syst`me International d’Unit ́s, which means international system of units. There are seven base SI units. These are listed below. All physical quantities have units which can be built from these seven base units. These seven units were defined to be the base units. So, it is possible to create a different set of units by defining a different set of base units. These seven units are called base units because none of them can be expressed as combinations of the other six. This is identical to bricks and concrete being the base units of a building. You can build different things using different combinations of bricks and concrete. The 26 letters of the alphabet are the base units for a language like English. Many different words can be formed by using these letters.
Base Quantity | Name | Unit |
Length | Metre | m |
Mass | Kilogram | Kg |
Time | Second | S |
Electric current | Ampere | A |
Ammount of sustance | Mole | mol |
Temperature | Kelvin | K |
Luminous intensity | Candela | cd |
It is very important that you are aware that different systems of units exist. Furthermore, you must be able to convert between units. Being able to change between units (for example, converting from millimetres to metres) is a useful skill in Science.
You may never know what results come of your action, but if you do nothing there will be no result.” ~ Mahatma Gandhi
We cannot become what we need to be by remaining what we are.
If you FAIL to PLAN then you are PLANING to FAIL.
here is the paper with mark scheme… Good Luck
Students you will have your test 2 in coming sunday 08th may. please dont forget to try the given specimen paper given below. practice make perfact. Good Luck.
Specimen Paper PHY003 PHY003 UT2
Marking Scheme of PHYoo3PHY003 UT2ms
The following Pdf file will give you how you could carry out with your assignment. Dur Date of the Assignment is 20th April 2011
Engineering Science assignment
The documentations of the assignments need to be improved. Most of the Assignment’s blue prints not much relevant with the solid project. And some of the assignments were exact copy of wikipedia. I advise student not to rely on wikipedia for educational resources.
Most of the presentations seen were fascinating and have done very well though write up is not relevant with it. Marks allocated to write up is 35 out of 50 and presentation 15 out of 35.
Mark sheet of the assignment is given below.
Thank you
Engineering Science -1 is a pre-requisite module for the students enrolled in advanced certificate in Engine repair and maintenance , welding, building construction and refrigeration.
The following link will provide you excess to unit out line of engineering science-1 , semester one 2011. This will give you the idea of topic that will be covered during the semester one of 2011
unit outline – This is not the finalised copy but this will help you to prepare for your exams
speed n distance time graph ws
Energy Transfer, PE, KE and Efficiency
STILL MORE TO COME ………….