1-PRINCIPLES OF STATICS.pdf

CHAPTER I 1 – Engineering mechanics is the science which considers the effects of forces on rigid bodies. 2 – In statics we consider the effects and distribution of forces on rigid bodies which are and remain at rest. 3 – In dynamics we consider the motion of rigid bodi...

CHAPTER I 1 – Engineering mechanics is the science which considers the effects of forces on rigid bodies. 2 – In statics we consider the effects and distribution of forces on rigid bodies which are and remain at rest. 3 – In dynamics we consider the motion of rigid bodies caused by the forces acting upon them. 4 – Rigid body is a definite amount of matter the parts of which are fixed in position relative to each other. 5 – Force is that which changes, or tends to change the state of motion of a body. This definition applies to the external effect of a force. 6 – The internal effect of a force is to produce stress and deformation in the body on which the force acts. It is dependent on its point of application. 7 – Principle of Transmissibility states that the external effect of a force on a body is the same for all points of application along its line of action; i.e., it is independent of the point of application. 8 – The internal effect of a force is definitely dependent on its point of application. 9 – Force system is any arrangement where two or more forces act on a body or on a group of related bodies. 10 – Coplanar forces are when the lines of action of all the forces in a force system lie in one plane; otherwise, they are non-coplanar. 11 – Concurrent forces are forces whose lines of action pass through a common point. Those in which the lines of action are parallel are called parallel force systems. Those in which the lines of action neither are parallel nor intersect in a common point are known as non-concurrent force systems. 12 –Two forces are in equilibrium only when: a) equal in magnitude b) opposite in directions c) collinear in action 13 – A set of forces in equilibrium maybe added to any system of forces without changing the effect of the original system. 14 – Action and reaction forces are equal but oppositely directed. 15 – Free-body diagram is a sketch of the isolated body which shows only the forces acting upon the body. 16 – Applied forces are forces acting on the free body. 17 – Reaction forces are those exerted by the free body upon other bodies. 18 – Scalar quantities are quantities which possess magnitude only and can be added arithmetically. 19 – A vector of a quantity can be represented geometrically. 20 – Free vector is one which does not show the point of application of the vector. 21. Triangle Law – If two forces are represented by their free vectors placed tip to tail, their resultant vector is the third side of the triangle, the direction of the resultant being from the tail of the first vector to the tip of the last vector. 22 – If the angle between two forces becomes zero or 180 o, the forces are collinear. 23. Mechanics – the science that considers the motion of bodies under the action of forces. 24 – Trigonometric Functions Angle 15o 30o 45o 60o 75o sin 0.259 0.500 0.707 0.866 0.966 cos 0.966 0.866 0.707 0.500 0.259 tan 0.268 0.577 1.000 1.732 3.732 25. Statics – study of motionless system or systems that move with constant velocity. 26. Equilibrium – a body at rest or moving with constant velocity. 27. Vectors – quantities that add like forces. 28. Kinematics – concerned with rates of change of geometrical quantities in a moving system; it does not involve the concept of force. 29. Kinetics – treats the causes and the nature of motion that results from specified forces. 30. The relationships among position, velocity, and acceleration of a moving body are defined by kinematics. (ex. A thrown ball) 31. The relationship between forces that act on the body (e.g. wind and gravity) and the motion of the body involves kinetics. 32. Particle – a body whose size does not influence its response to the forces acting on it. 33. Scientific notation – the use of powers of 10 to display numbers. CHAPTER I 1. Engineering mechanics is the science which considers the effects of forces on rigid bodies. 2. In statics we consider the effects and distribution of forces on rigid bodies which are and remain at rest. 3. In dynamics we consider the motion of rigid bodies caused by the forces acting upon them. 4. Rigid body is a definite amount of matter the parts of which are fixed in position relative to each other. 5. Force is that which changes, or tends to change the state of motion of a body. This definition applies to the external effect of a force. 6. The internal effect of a force is to produce stress and deformation in the body on which the force acts. It is dependent on its point of application. 7. Principle of Transmissibility states that the external effect of a force on a body is the same for all points of application along its line of action; i.e., it is independent of the point of application. 8. The internal effect of a force is definitely dependent on its point of application. 9. Force system is any arrangement where two or more forces act on a body or on a group of related bodies. 10. Coplanar forces are when the lines of action of all the forces in a force system lie in one plane; otherwise they are non-coplanar. 11. Concurrent forces are forces whose lines of action pass through a common point. Those in which the lines of action are parallel are called parallel force systems. Those in which the lines of action neither are parallel nor intersect in a common point are known as non-concurrent force systems. 12.Two forces are in equilibrium only when: a) equal in magnitude b) opposite in directions c) collinear in action 13. A set of forces in equilibrium maybe added to any system of forces without changing the effect of the original system. 14. Action and reaction forces are equal but oppositely directed. 15. Free-body diagram is a sketch of the isolated body which shows only the forces acting upon the body. 16. Applied forces are forces acting on the free body. 17. Reaction forces are those exerted by the free body upon other bodies. 18. Scalar quantities are quantities which possess magnitude only and can be added arithmetically. 19. A vector of a quantity can be represented geometrically. 20. Free vector is one which does not show the point of application of the vector. 21. Triangle Law – If two forces are represented by their free vectors placed tip to tail, their resultant vector is the third side of the triangle, the direction of the resultant being from the tail of the first vector to the tip of the last vector. 22. If the angle between two forces becomes zero or 180 o, the forces are collinear. 23. Mechanics – the science that considers the motion of bodies under the action of forces. 24. Trigonometric Functions Angle 15o 30o 45o 60o 75o sin 0.259 0.500 0.707 0.866 0.966 cos 0.966 0.866 0.707 0.500 0.259 tan 0.268 0.577 1.000 1.732 3.732 25. Statics – study of motionless system or systems that move with constant velocity. 26. Equilibrium – a body at rest or moving with constant velocity. 27. Vectors – quantities that add like forces. 28. Kinematics – concerned with rates of change of geometrical quantities in a moving system; it does not involve the concept of force. 29. Kinetics – treats the causes and the nature of motion that results from specified forces. 30. The relationships among position, velocity, and acceleration of a moving body are defined by kinematics. (ex. A thrown ball) 31. The relationship between forces that act on the body (e.g. wind and gravity) and the motion of the body involves kinetics. 32. Particle – a body whose size does not influence its response to the forces acting on it. 33. Scientific notation – the use of powers of 10 to display numbers.