Download Mrs. Burns: 2012185859 Day 1 Physics consist of a variety of topics

Mrs. Burns: 2012185859
Day 1
Physics consist of a variety of topics. Mechanics is the study of motions.As we learn the new
language and the new laws of physics, the goal is to think about the meanings of the material and
its application. Kinematics is the study of motions using words, diagrams, etc.
Distance: Related to displacement. is how far you traveled.
Displacement: it is reference to wherever you started. There has to be a direction(plus or minus).
Net change in position relative to starting point(origin).
Speed: rate of change of position, how fast the object is moving. Distance/time
Velocity: same as speed but you must include direction. It is based on your displacement rather
than your distance. Displacement/time. Has to include the direction
Acceleration: how fast your speed or velocity changes.
Unit for distance: Meter
Unit for displacement: Meter
Speed: Meters over second
Acceleration: m/s squared
Symbol: D for distance, displacement. V for velocity and speed, a for Acceleration
Vector quantity: type of quantity. Distance: scaler, they don’t have direction.
Acceleration: Vector it has to do with increasing and decreasing speed.
4 types of motion:
At rest, Constant Speed or Velocity, Increasing or decreasing
At rest: no motion at all.
Constant Velcity: Covering the same amount of distance in the same amount of time. NO
Acceleration.
Increasing: starting slower and steadly getting larger. If the increase is irregular, we cannot
measure it.
Constant speed: change in position over in certain time. V av= change in d/ change in t
Instantaneious speed: it is relative to the whole trip. Its relative. Distance is shorter
Lab: Constant Speed
Objective- What does a graph of constant speed look like?
Hypothesis-Constant speed graph will look like a constant line without ups and downs.
Rationale- (What do you think?)
The graph is flat. The speed is not changing so it is a straight line.
It will be constant line going up without any other upas and downs.
Decreasing: starting faster and slowing down.
Shallow: 1.09
Steep: 1.46
Answer objectives? What does slope mean? What does R squared mean?
The answer for the objectives: The graph will look constant linear.
Slope means change in position over change in time.The slopes for the shallow graph was 1.09.
Meanwhile, the slope for the steep graph was 1.46.
When R squared is closer to one, it is better. R squared is the percentage of how accurate the best
fit line is. The R squared of this graph was 99.2. Thus the graph was accurate.
Homework
Lesson 1
a. Introduction to the language of Kinametics
-
Mechanics is the study of motion of objects.
-
As we learn the new material, our goal is to contain and understand the new material
and the application rather than memorizing.
-
Kinametics is the science explaining the motion of objects using words, diagrams,
etc.
-
The goal of Kimematics is to build a mental motion model and that serve to explain
the motion of the real world.
b. Scalers and Vectors
-
The study of Physics is directly related to Mathmetics
-
The Mathematical quantities that are used to describe the motion of object can be
divided into scalers and vectors
-
Scalers are quantity that is described only numerically.
-
Vectors are the quantity described by both number and direction.
c. Distance and Displacement
-
Distance and displacement may seem the same but they have distinctive definitions.
-
Distance: Scaler quantity explaining how much ground it covered during its trip.
-
Displacement: Vector quantity. It is a object’s overall change in position.
-
Scaler ignores direction but vector doesn’t
d. Speed and Velocity
-
Speed: Scaler, the rate at which an objects cover distance. A fast moving object has a
high speed.
-
Velocity: Vector, the rate at which an object changes its position. When a person
leaves and returns to the same place, the velocity is zero.
-
Velocity is direction aware. Speed is direction ignorant.
-
The direction can be noted easily; when an object is moving west, you simply say the
velocity is to the west.
-
Average speed is total distance over total time.
-
Instantaneious speed is the speed at any given instance or time.
e. Acceleration
-
Acceleration is vector quantity associated with how much velocity did an object
move.
-
Moving fast doesn’t mean large acceleration. Acceleration changes only if the
velocity increases.
-
Constant acceleration: when velocity changes by a constant amount by each second.
-
If an velocity is increased by a constant amount, the object is accelerating. However,
if the veolicty is constant, the object is moving constant.
-
Free-fall is a good example of acceleration.
-
The unit for acceleration is m/s/s, m/s squared.
-
If an object is slowing down, then its acceleration is in opposite direction of its
motion.
Lesson 2
a. Introduction to diagram
-
Diagram is important in the course of physics. Focus on the real world physics.
-
Two major diagrams are ticker tape diagram and vector diagram.
-
A long tape is attached to a moving object and a threaded divce that places tick upon
the tape thus leaving a trail of dots which shows the history of the movement of the
object.
-
The distance between the dots of the diagram represents object’s position change in
time inverval.Larger distance means the object moved fast during the time interval.
-
Through the diagram, the students can analyze if the object is moving in constant
velocity or accelerating.
b. Vector diagram
-
Vector diagram shows the velocity of moving object during its time.
-
The magnitude of vector quanity is represented by the size of vector arrow.
-
Vector diagram shows acceleration, momentum, force.
Graphic:
Day 2
Notes:
Motion diagram is a qualitative representation. No numbers, relative size and direction.
Motion diagrams are sequence of arrows representing velocity and acceleration.
At ‘at rest,’ velocity is zero and acceleration is also zero. No motion diagram.
Constant speed  accelerations is zero. -------- faster speed.
 direction changes. Direction that the arrow points is the direction of the object. If you have
smaller arrows you are moving slower and the bigger vector the object moves faster.
.>  -- increasing speed acceleration should be to the right
When it’s decreasing the velocity and acceleration points to the opposite direction.
Positive is right and up negative is down and left, through convention.
A is always zero when constant
VA are the same when its increasing
VA are negative when its decreasing.
--  > . positive V, negative A
 negative V A is zero
.> -- increasing V positive, A positive
Ticker tape diagram:
Spark timer is used more often.
X…X…X…X…X…X – constant
X..X…X….X……X………X- increasing
X………X…….X…..X….X…X..X.de creasing
You have to label toe start so you do not get confused.
Free Fall Lab Report
Objective: What is acceleration due to gravity?
Hypothesis:
The acceleration due to gravity is equal to 9.81m/s2
Procedure:
We hung the spark timer on the ceiling and let the spark tape go through the timer. The
tape was taped to a 100g mass. Then, we number the dots and measured the displacement
of each dots upto 28th dot with the meter stick. I designed the graph afterwards.
Data Table:
dot #
timer (s) displacement (m)
0
0
0.00
1 0.016667
0.60
2 0.033333
1.20
3
0.05
1.80
4 0.066667
2.60
5 0.083333
3.60
6
0.1
4.80
7 0.116667
6.30
8 0.133333
8.15
9
0.15
10.20
10 0.166667
12.60
11 0.183333
15.30
12
0.2
18.35
13 0.216667
21.70
14 0.233333
25.30
15
0.25
29.25
16 0.266667
33.60
17 0.283333
38.05
18
0.3
42.71
19 0.316667
47.75
20 0.333333
52.95
21
0.35
58.31
22 0.366667
64.15
23 0.383333
70.10
24
0.4
76.25
25 0.416667
82.80
26 0.433333
90.10
Graph:
Free Falling Lab Ticker Timing Lab
Analysis:
The graph represents the increasing velocity. The slope is velocity and it is polynomial
graph. The equation is d=Xt2+Yt. The X coefficient represents the half of the acceleration due to gravity
and Y coefficient represents the first value of velocity..
Percent error:
Acceleration due to gravity= 9.81
9.81/2= 4.905
4.905 – 4.8717=0.0333
0.0333/4.905=0.00678
Percent error=0.00678
Percent difference:
Class average: 4.54
4.54-4.872=-0.332
-0.332/4.54= -0.0731
Absolute value= 0.0731
Percen difference=0.0731
The percent error was 0.00678; this error results from frictions from the spark timer. The spark tape
causes friction from the spark timer as it went through. Air resistance is also possible for the cause of
error. However since the mass was dense and air resistance does not really affect dense materials, air
resistance would be considered tribule and would not take into account in this case.
Since my value for acceleration due to gravity was approximately 4.8, my result was more precise than
the class average which was 4.54.
Note:
Position time graph, for at rest it is a horizontal line. Slope is velocity and slope of horizontal line is zero.
For velocity time graph, since the velocity is zero, at rest graph must be on the x axis.
Constant speed graph. Position time graph it is a linear function. Slope of this graph is positive and
speed. VT graph will will be a horizontal line. If its positive line its in positive side of the graph. If its
negative, the object changes the direction. Negative direction.
Increasing speed to the right. PT graph the line is getting steeper.
PT for decreasing, steep first and shallow later. VY graph will look like going down.
Homework:
Lesson 1
a.
The meaning of shape for the PT graph
-
The shape and the slope of the PT graph represents important features of the motions of
an object.
-
When the car is moving in constant rate of speed, the curve shows a linear positive
constant line.
-
When the car is changing its velocity, the curve will not be constant but will have different
beginning and end.
-
The slope of PT graph represents the velocity of an object
If the velocity is constant the slope is constant)straight line). If the velocity is positive the
slope is positive also.
b.
Meaning of slope in PT graph
-
c.
Slope=velocity(e.g. small slope represents small velicty)
If a car is moving 15 m/s for five seconds, the graph will show a line increased by 15 every
second. Thus, the slope is also 15.
If velocity is 0 m/s, the slope is alos 0 slope.
Determining slope of the PT graph
-
Slope= Change in Y(in this case, the position)/ change in X(in this case, the time) or
rise/run.
Lesson 4
a.
The meaning of a shape for a VT graph
-
For velocity-time graph, constant velocity will be shown as a horizontal line. If the care is
traveling at the constant rate of 40 m.s, the horizontal line will be on 40 in y intercept.
-
If the velocity is increasing, the slope of the v-t graph will be positive (I’m not so sure about
the shape)*
-
The slope of v-t graph represents the acceleration.if the acceleration is zero the slope is
zero thus the line is horizontal. If the acceleration is increasing, the slope is positive.
-
The velocity will be positive whenever the line lies on positive side of the graph.
A person will know if the veloicity is increasing fast or slow by checking if the graph is steep
or shallow.
b.
Meaning of slope in v-t graph
-
V-t graph provides information about the acceleration
-
-
If a car is moving in a constant rate of 10 m/s, the v-t line will be horizontal because there
is no acceleration.
If the car is accelerating by 10 m/s/s, the graph will have a slope of 10 m/s/s
-
If the car was moving in a constant rate for 4 seconds and then start increasing speed by
2m/s/s in next 4 seconds, the slope for the first half will be 0 m/s/s and the slope for the
second half will be 2 m/s/s.
c.
Relating the shape to the motion(was not able to do due to a problem with the screen
reader)
d.
Determining the slope of a v-t graph
-
Slope= Change in y(in this case velocity)/change in x(in this case, time), or rise over run.
e.
Determining the are on the v-t graph
-
The plot of v-t graph not only provides information about acceleration but also
displacement.
-
The area of a shaded region from certain point from the line to x axis represents the
displacement.
-
The shaded area could be either rectangle, triangle, or trapezoid. The area can be found by
calculation using the appropriate formula for each shape.
Lesson 5
a.
Introduction to free-fall
-
Free falling object is an object under the control of gravity.
-
Free falling object is not influenced by air resistance. Any falling object(in earth) falls
downward at an accelerating rate of 9.8 m/s/s.
-
Free-fall is shown in physic classrooms by strobe light demonstration.
b.
The acceleration of gravity
-
Any falling object on earth is accelerating downwards at a rate of 9.8 m/s/s.
-
This numeric value is called “Acceleration of gravity,” and it is very important among the
scientists.
-
The symbol for acceleration of gravity is “g,” and it is often written as 10m/s/s to reduce
the complexity of a problem.
-
The value of acceleration of gravity is different according to the intensity of gravity.
c.
Representing free-fall by graphs
-
P-t graph: a curve representing the acceleration of an object. Also it has a negative slope
indicating the negative velocity. And it is a graph for increasing motion.
-
V-t graph: diagonal line indicating the acceleration. It starts from zero velocity and ends at
a large negative number showing the pattern of going downwards.
d.
How fast? And how far?
-
The formula for determining the velocity of a falling object is after a time of t seconds is
V = G*t.
final
Example: V final for 3 seconds= vf=9.8 m/s/s * 3
Vf= 29.4 m/s
-
The formula for the distance of a falling object is d= 0.5*G*t2
Example: distance of a fallen object for 2 seconds
D=0.5*9.8m/s/s*2*2  2*9.8 m/s/s= 19.6 m/s.
e.
The big misconception
-
Students will have a question about the rate of free falling.
-
The question is “wouldn’t the heavier object fall faster than the lighter object?”
-
The answer is no because the definition iof free fall is ‘the motion of objects under the sole
influence of gravity,’ and free falling object is not influenced by air resistance.
-
It is related to fore and mass; the rate of acceleration is directly related to force and
indirectly related to mass.
Link below is a video regarding the misconception of the concept of free fall. I copied and pasted it
because the video explains well and the video is also interesting.
http://www.youtube.com/watch?v=z6SrwUwVZ5Y&feature=fvst
Day 3
Notes:
Law of inertia: an object is in motion when it is in motion. And an object is at rest unless it is
acted upon.
At rest= static equal liberium V and A are all zero.
Dynamic equal liberium: when velocity is not zero but the acceleration is zero.
Force: push or pull external system.
The force cannot be carried. Force is only felt by direct contact. It is not save.
Threre is weight normal tension friction.
Symbol of weight: w, friction; f, Normal: N, Tention: T
Weight always points down, straight down. W= mass*gravity
Friction: when two surfaces erupted together. Static friction, rolling firction, etc.
Sometimes friction can help you. Friction is pararell to the surface opposite the direction of
motion.
Normal force: support force. It points perpendicular to the surface and through the system.
Tention is only caused by rope or chain. They have definite direction.
Lab 3
Objective: What is the relationship between A) net force and acceleration of an object and B)
mass of an object and its acceleration.
Hypothesis: rate of acceleration is directly related to the net force. On the other hand, the rate
of acceleration is indirectly related to the mass of an object.
Analysis: talk abut experimental error and reasons for it(friction). We ignored pullies too. The meanings
of the equating of the line.
First Graph
Second Graph
The first graph(net force and the rate of acceleration graph) is a linear graph meaning the relationship
between the net force and the rate of acceleration is proportional to each other. The slope of the line is
equal to the mass of the cart. The mass of the cart was 0.53 and the slope was approximately 0.545,
making the percent error 2.9 percent. This error is due to the friction between the cart and the track and
pulley adds some friction onto the cart as well.
The second graph(mass and the rate of acceleration graph) is an inverse graph. It means that the
relationship between the mass a nd the rate of acceleration is an inverse power. Therefkre, through this
experiment we deived an equation mass= force/the rate of acceleration.
Homework:
Newton’s Law
Lesson 1
a.
Newton’s first law
-
Isaac Newton is a 17th century scientist who discovered three laws of motion. The first law
is called the law of inertia.
-
First law: “an object at rest stays at rest and an object stays in motion with the same speed
unless some type of force is acted upon the object.”
b.
The law explains that the object keep on doing what they were doing.
Inertia and mass
-
Concept before Newton’s discovery: Objects have tendancy to stop the motion.
-
Gallileo, a scientist prior to Newton, discovered friction; forces do not necessarily move an
object. Newton based his idea upon this concept of friction.
-
Mass is the measure of amount of inertia
-
The object’s tendancy to resist the motion is controlled by the object’s mass.
-
The lighter the object, the smaller the resistance of an object.
c.
State of motion
-
d.
State of motion is defined by velocity.
Balanced and unbalanced forces
-
-
When all the forces acted upon the object is balanced the object is in the equal liberium
thus, the object does not accelerate or move.
Free body diagrams explain forces that are being exerted on to a certain object.
Unbalanced force moves an object. N and w balance out each other but the f does not
have any other force to balance it out. There for an object moves due to the f.
Lesson 2
a. The meaning of force
-
Force is push and pull caused by an interaction between two objects
-
Contact force: when two objects are physically contacting each other.Frction, weight, air
resistance force are some examples.
-
Action idstance force is opposite of contact force. When they are not contacting each
other. Gravitation is an example.
-
Force is a vector quantity.
b. Type of force
-
Aplied force: force that is applied on an object by a person or something.
-
Gravity force: also known as weight. It is the attraction from the center of Earth or Moon.
The symbol is w and w always points downward.
-
Normal force: symbol is N. It is always perpendicular force going through an object.
Normal force is support force.
-
-
Friction force: symbol is f. It is pararell to an object and opposite of the direction of the
object’s motion. Friction force often stops an object from motion. Two type of friction:
sliding and static.
Tention force: has to do with ropes and chains. The symbol is T.
There is also spring force(force from a spring), and air resistance force(the force when an
object is disturbed by the air.)
c. Drawing FBD
-
FBD is diagram showing the magnitude and direction of certain force exerted to an object
in a given situation.
-
Label the type of force and just draw an arrow to the direction that the force is being
exerted. FBD is a type of a vector diagram.
d. Determining the net force
-
Net force is a vector sum of all the value of force acted upon the obje
Day 4
Notes:
A= M1*G/M1+M2
Minimum: zero Maximum: 9.8
When M1 is smaller than M2: 0<x<4.9
M1 is greater than M1: 4.9<x<9.8
A=net force?mass
Tension minus the weight divied by the mass.
Friction: the reason is unknown. Coefficient of friction is not a force of friction. It is a number
that represents how two surfaces interact when they tty to slide them across each other. It’s a
ratio no units.
gym floor
0.286
table
concrete
0.486
floor tile
floor tile
0.278
gym floor
table top
0.205
pavers
Carpet
0.4
carpet
Pavers
0.358
concrete
Homework
Lesson 3
a.
Newton’s second law
-
Second law states that the acceleration of an object is proportianlly related to the net
force and inversely related to the mass.
-
Equation:a=F/m, could be turned to F=ma
-
1N is amount of force given to an object with 1 kg mass an acceleration of 1 m/s/s.
-
Diection of net force and the acceleration of an object is the same.
b.
The big misconception(Nothing to write about)
c.
Finding acceleration
-
d.
If the student can figure out the vale of net force and the mass of an object, the
acceleration is easy to find.
Finding individual forces
-
e.
If a student knows the acceleration and the mass of ab object, net force can be found using
equations.
Free fall and air resistance
-
Object that is undergoing the free fall does not face air resistance much because it is solely
under the power of gravity.
-
Since Newton’s second laow states f=ma, mass and acceleration balances out. If something
has heavy mass its acceleration has to be small. If an object’s mass is small then the object
accelerate fast.
-
Net force/m=9.8N/kg, it is called gravitational field strength.
-
If there is an air resistance, more massive object falls faster than the less massive object.
-
The air resistance depends upon the speed of an object.
-
f.
More massive object has faster rate of acceleration because greater force of gravity acts
upon the object untill the air resistance equals the gravity force.
Double trouble
-
-
Two body problems most likely have unknown values for the acceleration and the net
force.
Two analysis methods: system(acceleration), individual(force).
Day 5
Notes:
Terminal velocity: dynamic equal liberium, when air resistanceand gravity equals out.
Homework:
Lesson 4
a.
Newton’s third law
-
Force is pull and push upon an object by contacting the object.
-
When two objects interact each other they exert forces to each other.
-
Action and reaction forces are two type of exerted force.
-
The reaction has to be equal and opposite to the previous action
b.
Identifying action and reaction force paris
-
Forces come in pairs; action reaction force pairs
-
If a student is sitting down on a chair, the force from the student is exerted downwards to
the chair. The reaction force coming from the chair is going upwards to the student.