CAPÍTULO II: MARCO TEÓRICO
2.1. Comprensión Lectora
2.1.3. Factores Relacionados con la Comprensión de Lectura
instances of existence
or non- existence of
equilibrium in day to
day life
2.3 Explains the equilibrium of a particle under the action of three forces as a particular case
2.4 Explains the effect of forces on a rigid body
•
Resultant of any two forces equal in magnitude and opposite in direction to the third force•
Law of triangle forces and its converse•
Lami’s theorem and its applications•
Forces acting on a rigid body• Concept of a rigid body
• Principle of transmission of forces
• Explaining the translational and rotational effect of a force
• Defining the moment of a force about a point
• Physical meaning of moment
• Magnitude and sense of moment of a force about a point
• Dimensions and units of moment
• Geometric interpretation of moment
•
Algebraic sum of the moments of the component forces about a point on the plane of a system of coplanar forces•
General principle about moment of forces06
2.5 Explains the effect of two forces acting on a rigid body
2.6 Analyses a system of coplanar forces
•
Resultant of two forces• When the two forces are not parallel
• When the two forces are parallel and like
• When the two forces are parallel and unlike
•
Equilibrium of two forces•
Definition of a couple• Magnitude and sense of the moment of a couple
• the moment of a couple is independent of the point about which the moment taken
•
Equivalence of two coplanar couples•
Equilibrium of two couples•
Composition of co-planar couples•
A couple and a single force acting in the plane of the couple is equivalent to the single force acting at some other point parallel to its original direction•
A force acting at any point is equivalent to an equal and parallel force acting at any other point together with a couple•
Reducing a system of coplanar forces to a single06
2.7 Explains the equilibrium ofthree coplanar forces acting on a rigid body as a particular case
2.8 Investigates the effect of frictionon equilibrium in terms of its properties
•
Magnitude, direction and the line of action of the resultant•
Conditions for the reduction of system of coplanar forces to• a single force, R ≠ 0 ( X ≠ 0 or Y ≠ 0 )
• a couple, R= 0 (X= 0 and Y= 0) and G ≠ 0
• equilibrium X = 0, Y = 0 and G = 0
•
forces must either be concurrent or be all parallel•
Use of• Law of triangular force and its converse
• Lami’s theorem
• Cot rule
• Geometrical properties
• Resolving in two perpendicular directions
•
Frictional force and its nature•
Introducing smooth and rough surfaces•
Advantages and disadvantages of friction•
Limiting frictional force•
Laws of friction•
Definition of coefficient of friction•
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2.9 Applies the systems of coplanar forces to determine the details about the reactions at smooth joints
2.10 Determines the stresses in the rods of a framework with smoothly jointed rods
2.11 Applies various techniques to determine the centre of mass of symmetrical uniform bodies using definition
•
Types of simple joints•
Difference between a movable joint and a rigid joint•
Forces acting at a smooth joint•
Introduces a framework with light rods•
Conditions for the equilibrium of each joint in the framework• Bow’s notation, stress diagram
• Calculation of forces
•
Definition of centre of mass•
Centre of mass of a plane body symmetrical about a line• Uniform thin rod
• Uniform rectangular lamina
• Uniform circular ring
• Uniform circular disc
•
Centre of mass of a body symmetrical about a plane10
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2.12 Finding the centre of mass of simple geometrical bodies using definition and integration
2.13 Finds the centre of mass (centreof gravity)of composite bodies and remaining bodies assuming that the centre of mass and centre of gravity coincide
2.14 Determines the stability of bodies in
•
Using the fact that when a plane lamina is divided into thin strips the centre of mass lies on the line through their mid points• Uniform triangular lamina
• Uniform lamina in the shape of a parallelogram • Centre of mass of continuous symmetrical bodies • By dividing into elements
• Uniform circular arc, uniform sector
•
Finding the centre of mass of uniform symmetrical bodies• Uniform hollow (or solid) cone
• Uniform hollow (or solid) hemisphere
•
Rotation of an elemental plane•
Introducing centre of gravity•
Coincidence of the centre of gravity and centre of mass•
Centre of mass (centre of gravity) of symmetrical composite bodies•
Centre of mass (centre of gravity) ofsymmetrical remaining bodies
•
Suspended bodies04
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3.1 Uses graphs to solve problems about motion in a straight line
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Distance, its dimensions and units
•
Speed, its dimensions and units•
Average speed, instantaneous speed, uniform speed•
Position co-ordinates•
Displacement, its dimensions and units•
Velocity, dimensions and units•
Average velocity, instantaneous velocity, uniform velocity•
Displacement-time curve• Average velocity between two positions
• Instantaneous velocity at a point
•
Definition of acceleration•
Average acceleration, instantaneous acceleration, uniform acceleration and retardation•
Dimensions and units of acceleration•
Velocity-time curve•
Gradient of the graph is equal to the instantaneous acceleration at any instant•
In any velocity-time curve the area between the10