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96 Cards in this Set
- Front
- Back
- 3rd side (hint)
Define: Vector quantity |
A quantity that has both magnitude and direction |
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Define: kinematics |
The study of motion |
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What is this symbol? |
Average speed |
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The equation for average speed |
d is the distance travelled in total time.
Average speed is the total distance travelled divided by the total time of travel. (The symbol for average speed, vav , is taken from the word “velocity.”) The equation for average speed is where d is the total distance travelled in a total time t.
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Define instantaneous speed |
The speed at a particular instance |
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Average velocity |
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Scalar quantity |
Speed, distance, and time are examples of a scalar quantity, a quantity that has magnitude (or size) only, but no direction. |
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Summary - Uniform Motion |
Key Points A vector quantity has both magnitude and direction. Examples areposition, displacement, and velocity.• Position, d , is the distance and direction of an object from a referencepoint. Displacement, d, is the change in position of an object from areference point.• Average velocity is the ratio of the displacement to the time interval,or v av dt.• The straight line on a position-time graph indicates uniform motion andthe slope of the line represents the average velocity between any two times.• The area under a line on a velocity-time graph represents the displacementbetween any two times. |
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Position |
A common vector quantity is position, which is the distance and direction of an object from a reference point. For example, the position of a friend in your class could be at a distance of 2.2 m and in the west direction relative to your desk. The symbol for this position is = 2.2 m [W]. |
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Displacement |
Another vector quantity is displacement, which is the change in position of an object in a given direction. |
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Variables that can be measured directly |
variables that can be measured directly are usually time and either position or displacement. The third variable, velocity, is often obtained by calculation. |
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Velocity time graph |
velocity-time graph can be used to find the displacement during various time intervals. |
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Average velocity in two dimensions |
Average Velocity in Two Dimensions
Just as for one-dimensional motion, the average velocity for two-dimensional motion is the ratio of the displacement to the elapsed time. Since more than one displacement may be involved, the average velocity is described using the resultant displacement. |
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Relative velocity |
The velocity of a body relative to a particular frame of reference is called relative velocity. |
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Acceleration |
Calculating Acceleration
Acceleration is defined as the rate of change of velocity. Since velocity is a vector quantity, acceleration is also a vector quantity. The instantaneous acceleration is the acceleration at a particular instant. For uniformly accelerated motion, the instantaneous acceleration has the same value as the average acceleration. The average acceleration of an object is found using the equation |
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Average acceleration |
Back (Definition) |
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What is the process of deriving equations? What are the three main stages: |
1. State the given facts and equations.
2. Substitute for the variable to be eliminated.
3. Simplify the equation to a convenient form. |
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What is the average velocity for two-dimensional motion |
It is the ratio of the displacement to the elapsed time. |
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Frame of Reference |
coordinate system relative to which a motion can be observed |
Any motion observed depends on the frame of reference chosen. |
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Summary - Two dimensional Motion |
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What is accelerated motion |
nonuniform motion that involves change in an object’s speed or direction or both |
If an object is changing it's speed in a non-uniform fashion, its acceleration is non-uniform. |
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uniformly accelerated motion
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motion that occurs when an object travelling in a straight line changes its speed uniformly with time |
Also occurs when an object travelling in a straight line slows down uniformly. |
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Define: instantaneous velocity |
velocity that occurs at a particular instant |
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Define: Tangent |
A straight line that touches a curve at a single point and has the same slope as the curve at that point |
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What is Tangent Technique |
A method of determining velocity on a position-time graph by drawing a line tangent to the curve and calculating the slope |
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instantaneous velocity |
velocity that occurs at a particular instant |
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Summary Uniform Acceleration |
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Acceleration due to gravity |
The vector quantity 9.8 m/s2 [down], or 9.8 m/s2 [↓], occurs so frequently inthe study of motion that from now on, we will give it the symbol g , which represents the acceleration due to gravity |
(Do not confuse this g with the g used as the symbol for “gram.”)
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Summary card of Acceleration |
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terminal speed: |
maximum speed of a falling object at which point the speed remains constant and there is no further acceleration |
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derived unit: |
unit that can be stated in terms of the seven base units
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base unit: |
Unit from which other units are derived or made up |
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resultant displacement |
vector sum of the individual displacements |
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Force |
a push or a pull |
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What are the fundamental forces? |
Forces are classified into four categories—gravitational, electromagnetic, strong nuclear, and weak nuclear |
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gravitational force or force of gravity: |
force of attraction between all objects |
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Electromagnetic force |
force caused by electric charges |
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strong nuclear force |
Force that holds protons and neutrons together in the nucleus of an atom |
The strong nuclear force holds the protons and neutrons together, even though the protons are influenced by the electric force of repulsion. This nuclear force is a short-range force but is much stronger than the electromagnetic force. It is significant only when the particles are close together
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weak nuclear force: |
force responsible for interactions involving elementary particles such as protons and neutrons |
This type of force is noticed only at extremely small distances.
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Normal force: |
Force perpendicular to the surfaces of the objects in contact |
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Friction |
Force between objects in contact and parallel to contact surfaces |
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Tension: |
Force exerted by string, ropes, fibres, and cables |
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Newton |
newton: (N) the SI unit of force |
The newton is a derived SI unit, which means that it can be expressed as acombination of the base units of metres, kilograms, and seconds. For theremainder of your study of forces and motion, it is important that you performcalculations to express distance in metres, mass in kilograms, and time in seconds. In other words, all units must conform to the preferred SI units of metres,kilograms, and seconds. |
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system diagram: |
sketch of all the objects involved in a situation |
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free-body diagram: |
(FBD) drawing in which only the object being analyzed is drawn, with arrows showing all the forces acting on the object |
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Forces in Nature |
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Dynamics |
the study of the causes of motion |
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Inertia: |
the property of matter that causes a body to resist changes in its state of motion |
The amount of inertia an object possesses depends directly on its mass: the greater the mass, the greater the inertia the body possesses |
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first law of motion: |
if the net force acting on an object is zero, the object will maintain its state of rest or constant velocity |
Summarize - Newton’s first law of motion by stating four important results of it: (a) Objects at rest tend to remain at rest. (b) Objects in motion tend to remain in motion. (c) If the velocity of an object is constant, the net external force acting on it must be zero. (d) If the velocity of an object is changing in either magnitude or direction or both, the change must be caused by a net external force acting on the object. This fact sets the stage for experimentation in dynamics |
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Summary - Newton's First Law of Motion |
Galileo’s real and virtual experiments led the way for Newton to formulate his three laws of motion. • The net force acting on an object, Fnet, is the vector sum of all the forces acting on the object. • Newton’s first law of motion, often called the law of inertia, states that ifthe net force acting on an object is zero, the object will maintain its state ofrest or uniform velocity. • The first law of motion is observed and applied in many situations,including the need for restraint systems in automobiles. |
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Second law of motion: |
if the net external force on an object is not zero, the object accelerates in the direction of the net force, with magnitude of acceleration proportional to the magnitude of the net force and inversely proportional to the object’s mass |
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Equations - 2nd Law of Motion |
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Summary - Second Law of Motion |
Newton’s second law of motion relates the acceleration of an object to the mass of the object and the net force acting on it. The equation is a = F net/m or F net = ma . • Newton’s second law is applied in many problem-solving situations. |
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Third law of motion: |
For every action force, there is a reaction force equal in Third Law of Motion magnitude, but opposite in direction |
Newton’s third law of motion, which always involves two objects, states that for every action force, there is a reaction force equal in magnitude, but opposite in direction. • Action-reaction pairs of forces are applied in many situations, such as a person walking, a car accelerating, and a rocket blasting off into space. |
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Force Field |
space surrounding an object in which the object exerts a force on other objects placed in the space |
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gravitational field strength: |
the amount of force per unit mass acting on objects in the gravitational field |
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mass: |
the quantity of matter in an object |
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weight: |
the force of gravity on an object |
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Gravitational Force on Earth’s Surface |
Earth’s gravitational field is the space surrounding Earth in which the forceof gravity has an effect.• On Earth’s surface, the average gravitational field strength isg = 9.8 N/kg [↓].• Mass is the quantity of matter (measured in kilograms) and weight is theforce of gravity (measured in newtons and determined using the equationFg= mg ).• The magnitude of g decreases as the distance from Earth’s centre increases,so this magnitude is smaller at higher altitudes, and it is greater at the polesthan at the equator because Earth is slightly flattened at the poles.• An object orbiting another object maintains its orbit by constantly free falling toward the central body. For example, the International Space Station and its contents constantly free fall toward Earth. |
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Law of universal gravitation: |
The force of gravitational attraction between any two objects is directly proportional to the product of the masses of the objects, and inversely proportional to the square of the distance between their centres. |
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Symbols - law of universal gravitation |
FGis the force of gravitational attraction between any two objects.m1 is the mass of one object.m2 is the mass of a second object.d is the distance between the centres of the two objects.(Objects are assumed to be spherical.)
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Equation: Law of universal gravitation |
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5(a) For an object undergoing free fall, the weight, Fg, is the force which causes the object to accelerate downward. (b) When an object rests on a horizontal surface, the object’s weight causes a downward force on the surface. This force is balanced by an upward force of the surface, the normal force, on the object. (c) The upward force required to raise an object at a constant speed is equal in magnitude to the object’s weight. |
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Static friction: |
The force that tends to prevent a stationary object from starting to move
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Starting friction: |
The amount of force that must be overcome to start a stationary object moving |
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kinetic friction: |
The force that acts against an object’s motion in a direction opposite to the direction of motion |
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What is a bearing |
A bearing is a device containing many rollers or balls that reduce friction while supporting a load (Figure 3). Bearings change sliding friction into rolling friction, reducing friction by up to 100 times. |
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Summary - The Effects of Friction |
Friction acts parallel to 2 surfaces in contact in a direction opposite to the motion or attempted motion of an object. Static friction tends to prevent a stationary object from starting to move Kinetic friction acts against an object's motion; it is usually less than static friction Fro an object to maintain uniform velocity, the net force acting on it must be zero, so for an object moving at uniform velocity on a horizontal surface, the applied horizontal force must be equal in magnitude to the kinetic friction. Unwanted friction can be reduced by changing sliding to rolling, by using bearings and by using lubrication. The extent to which certain factors affect friction, such as the types of surfaces in contact or the mass of the object, can be determined using a controlled experiment. |
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Coefficient of friction: |
Ratio of the magnitude of friction to the magnitude of the normal force |
The coefficient of friction is a number that indicates the ratio of the magnitude of the force of friction, Ff, between two surfaces to the magnitude of the force perpendicular to these surfaces. Recall that the magnitude of the force perpendicular to the surface is called the normal force, FN, so the coefficient of friction is the ratio of Ff to FN. |
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Equation - coefficient of friction |
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Coefficent of Kinetic friction |
The coefficient of kinetic friction is the ratio of the magnitude of the kinetic friction to the magnitude of the normal force. |
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The coefficient of static friction |
is the ratio of the magnitude of the maximum static friction to the magnitude of the normal force. |
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Summary - Analyzing Motion with Friction |
The coefficient of friction, m, is the ratio of the magnitude of the force of friction to the magnitude of the normal force between two surfaces in contact • These coefficients can be determined using a controlled experiment in which a horizontal applied force is used to move an object with constant velocity across a horizontal surface. Problem-solving skills developed throughout this unit can be synthesized in order to solve problems that include friction and coefficients of friction. |
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Energy: |
The capacity to do work |
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Heat: |
the transfer of energy from a warmer body or region to a cooler one |
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Forms of Energy |
Thermal Electrical Radiant Nuclear potential Gravitational Potential Kinetic Elastic potential Sound Chemical Potential |
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thermal energy |
The atoms and molecules of a substance possess thermal energy. The more rapid the motion of the atoms and molecules, the greater the total thermal energy |
Thermal energy in the boiling water transfers tothe pasta to cook it. |
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electrical |
This form of energy is possessed by charged particles. The charges can transfer energy as they move through an electric circuit. |
Electrical energy delivered to the stoveheats the water in the pot |
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Radiant |
Radiant energy travels by means of waves without requiring particles of matter. |
The Sun emits radiant energies, such as infrared radiation, visible light, and ultraviolet radiation. The Sun’s energy comes from nuclear fusion reactions in its core |
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Nuclear Potential |
The nucleus of every atom has stored energy. This energy can be released by nuclear reactions such as nuclear fission and nuclear fusion. |
The Sun emits radiant energies, such as infrared radiation, visible light, and ultraviolet radiation. The Sun’s energy comes from nuclear fusion reactions in its core |
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Gravitational Potential |
A raised object has stored energy due to its position above some reference level. |
At the highest position above the trampoline, this athlete has the greatest amountof gravitational potential energy. Theenergy changes to kinetic energy as herdownward velocity increases. The kineticenergy then changes into elastic potential energy in the trampoline to help herbounce back up. |
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kinetic |
Every moving object has energy of motion, or kinetic energy. |
At the highest position above the trampoline, this athlete has the greatest amountof gravitational potential energy. The energy changes to kinetic energy as herdownward velocity increases. The kinetic energy then changes into elastic potential energy in the trampoline to help herbounce back up. |
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Elastic potential |
This potential energy is stored in objects that are stretched or compressed. |
At the highest position above the trampoline, this athlete has the greatest amountof gravitational potential energy. The energy changes to kinetic energy as herdownward velocity increases. The kinetic energy then changes into elastic potential energy in the trampoline to help herbounce back up. |
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Sound |
This form of energy, produced by vibrations, travels by waves through a material to the receiver |
Chemical potential energy is released when fireworks explode. Some of that energy is changed into sound energy |
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Chemical potential |
Atoms join together in various combinations to form many different kinds of molecules, involving various amounts of energy. In chemical reactions, new molecules are formed and energy is released or absorbed. |
Chemical potential energy is released when fireworks explode. Some of that energy is changed into sound energy |
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Energy transformation: |
the change from one form of energy to another |
We can summarize these changes using an energy transformation equation. For the microwave oven example described above, the equation is electrical energy → radiant energy → thermal energy |
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work: |
The energy transferred to an object by an applied force over a measured distance |
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Relationships between work & applied force |
Using the symbols W for work, F for the magnitude of the applied force,and d for the magnitude of the displacement, the relationships among these variables are |
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What is the Newton metre |
Since force is measured in newtons and displacement is measured in metres, work is measured in newton metres (N•m). The newton metre is called the joule(J) in honour of James Prescott Joule, an English physicist who studied heat and electrical energy (Figure 2). Since the joule is a derived SI unit, it can be expressed in terms of metres, kilograms, and seconds |
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Examples of Zero Work |
Zero Work Situations exist in which an object experiences a force, or a displacement, or both, yet no work is done on the object. If you are holding a box on your shoulder, you may be exerting an upward force on the box, but the box is not moving, so the displacement is zero, and the work done on the box, W = Fd, is also zero.In another example, if a puck on an air table is moving, it experiences negligible friction while moving for a certain displacement. The force in the direction of the displacement is zero, so the work done on the puck is also zero. In a third example, consider the force exerted by the figure skater who glides along the ice while holding his partner above his head (Figure 5). There is both a force on the partner and a horizontal displacement. However, the displacement is perpendicular (not parallel) to the force, so no work is done on the woman. Of course, work was done in lifting the woman vertically to the height shown. |
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How is work measured? |
Work is a scalar quantity measured in joules (J). |
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What is the value when force & displacement are in the same direction? |
If the force and displacement are in the same direction, the work done by the force, is a positive value. If the force and displacement are in opposite directions, the work done is a negative value. |
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Position |
Back (Definition) |
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Describe displacement |
Back (Definition) |
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Vector scale diagrams |
They show the vectors associated with a displacement drawn to a particular scale |
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What is a directed line segment? |
A straight line between two points with a specific direction |
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