Questions and Answers
What is the primary characteristic of an object in static equilibrium?
What type of support prevents both translation and rotation of an object?
What is the method used to analyze trusses by considering the equilibrium of each joint?
What is the point where the weight of an object can be considered to act?
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What is the turning effect of a force around a pivot point or axis?
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What is the formula to calculate the moment of a force?
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What type of equilibrium occurs when the sum of forces in all directions is zero?
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What is the purpose of a support in statics?
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Study Notes
Forces
- A force is a push or pull that causes an object to change its motion or shape
- Forces can be classified as:
- External forces: acting from outside the system (e.g. friction, normal force, tension)
- Internal forces: acting within the system (e.g. gravity, electromagnetic forces)
- Forces have both magnitude (amount of force) and direction
Newton's Laws of Motion
- First Law (Law of Inertia): an object at rest will remain at rest, and an object in motion will continue to move with a constant velocity, unless acted upon by an external force
- Second Law (F=ma): the acceleration of an object is directly proportional to the force applied and inversely proportional to its mass
- Third Law (Action-Reaction): for every action, there is an equal and opposite reaction
Equilibrium
- Static Equilibrium: a state where the net force acting on an object is zero, resulting in no acceleration
- Translational Equilibrium: a state where the sum of forces in all directions is zero
- Rotational Equilibrium: a state where the sum of torques (rotational forces) is zero
Support Reactions
- Supports: external forces that prevent an object from translating or rotating
- Reactions: forces exerted by supports to maintain equilibrium
- Types of supports:
- Fixed support: prevents both translation and rotation
- Hinged support: allows rotation but not translation
- Sliding support: allows translation but not rotation
Trusses
- A truss is a structure composed of triangular elements connected at joints
- Method of Joints: a method used to analyze trusses by considering the equilibrium of each joint
- Method of Sections: a method used to analyze trusses by considering the equilibrium of each section of the truss
Centers of Gravity
- Center of Gravity (CG): the point where the weight of an object can be considered to act
- Center of Mass (CM): the point where the mass of an object can be considered to act
- For uniform objects, CG and CM are the same point
Moment of a Force
- Moment of a Force: the turning effect of a force around a pivot point or axis
- Calculated by: M = r x F, where M is the moment, r is the distance from the pivot point to the line of action of the force, and F is the force
Forces
- Force is a push or pull that causes an object to change its motion or shape
- Classified into external forces (friction, normal force, tension) and internal forces (gravity, electromagnetic forces)
- Forces have both magnitude (amount of force) and direction
Newton's Laws of Motion
First Law (Law of Inertia)
- An object at rest remains at rest, and an object in motion continues to move with constant velocity unless acted upon by an external force
Second Law (F=ma)
- Acceleration of an object is directly proportional to the force applied and inversely proportional to its mass
- Force (F) equals mass (m) times acceleration (a)
Third Law (Action-Reaction)
- For every action, there is an equal and opposite reaction
Equilibrium
Static Equilibrium
- Net force acting on an object is zero, resulting in no acceleration
Translational Equilibrium
- Sum of forces in all directions is zero
Rotational Equilibrium
- Sum of torques (rotational forces) is zero
Support Reactions
- Supports are external forces that prevent an object from translating or rotating
- Reactions are forces exerted by supports to maintain equilibrium
- Fixed support prevents both translation and rotation
- Hinged support allows rotation but not translation
- Sliding support allows translation but not rotation
Trusses
- Truss is a structure composed of triangular elements connected at joints
- Method of Joints analyzes trusses by considering equilibrium of each joint
- Method of Sections analyzes trusses by considering equilibrium of each section of the truss
Centers of Gravity
- Center of Gravity (CG) is the point where an object's weight can be considered to act
- Center of Mass (CM) is the point where an object's mass can be considered to act
- For uniform objects, CG and CM are the same point
Moment of a Force
- Moment of a Force is the turning effect of a force around a pivot point or axis
- Calculated by: M = r x F, where M is the moment, r is the distance from the pivot point to the line of action of the force, and F is the force
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Description
Quiz about forces, their classification, and Newton's laws of motion. Learn about external and internal forces, magnitude, and direction.
