4.3 Newton’s Second Law of Motion: Concept of a System
3 min read•june 18, 2024
of Motion is a cornerstone of physics. It explains how forces affect motion, stating that an object's acceleration is directly proportional to the acting on it and inversely proportional to its .
This law helps us understand and predict object motion in various situations. It's crucial for analyzing everything from simple everyday movements to complex systems in engineering and space exploration.
Newton's Second Law of Motion: Concept of a System
Net force and system concepts
Net force represents the vector sum of all forces acting on an object or determines the acceleration of the object or represented by the equation Fnet=ma
originates from outside the system being considered can cause a change in the motion of the system (, gravity, applied forces)
System refers to a collection of objects or particles being studied or analyzed can be defined based on the problem or situation at hand the boundaries of the system determine which forces are considered external or internal
The is the point at which the entire mass of a system can be considered to be concentrated for the purpose of calculating its motion
Newton's Second Law implications
Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass mathematically expressed as Fnet=ma the direction of the acceleration is in the same direction as the net force
The motion of an object or system can be predicted by analyzing the forces acting on it
The acceleration of an object depends on both the magnitude and direction of the net force
Objects with greater mass require a larger force to achieve the same acceleration as objects with less mass
If the net force on an object is zero, the object will maintain a constant velocity or remain at rest ()
states that for every action, there is an equal and opposite reaction, which is crucial in understanding the interactions between objects in a system
Weight vs mass calculations
is the force exerted on an object due to gravity calculated using the equation w=mg
w is the vector
m is the mass of the object
g is the acceleration due to gravity (approximately 9.81m/s2 on Earth)
Mass is a measure of an object's or resistance to acceleration an intrinsic property of the object that does not change with location measured in kilograms (kg) in the SI system
Weight is a force and is measured in newtons (N), while mass is a scalar quantity measured in kilograms (kg)
Weight depends on the gravitational field strength and varies with location (Earth, Moon, space), while mass remains constant
On Earth, an object's weight is related to its mass by a factor of approximately 9.81m/s2, but this factor changes on other planets or in space
Forces and Interactions
Friction is a force that opposes the relative motion between two surfaces in contact
is the perpendicular force exerted by a surface on an object in contact with it
is the force transmitted through a string, rope, cable, or other similar objects when pulled tight by forces acting from opposite ends
is the product of an object's mass and velocity, and its change is related to the applied to the object
Key Terms to Review (30)
Atomic mass: Atomic mass is the weighted average mass of an atom's naturally occurring isotopes, measured in atomic mass units (amu). It reflects both the mass and relative abundance of each isotope.
Center of mass: The center of mass is the point in a body or system of bodies where the entire mass can be considered to be concentrated for the purpose of analyzing translational motion. It is the average location of all the mass in a system.
Center of Mass: The center of mass is a point within an object or system of objects where the object's mass is concentrated. It is the point at which the object's weight can be considered to act, and it is the point around which the object's rotational motion is determined.
External force: An external force is any force that originates from outside a system and influences the motion of objects within that system. It can cause changes in velocity, direction, or state of an object's motion.
External Force: An external force is a force that acts on an object from outside the system being considered. It is a force that originates from a source external to the object or system, and it can influence the object's motion or state of equilibrium.
Force Diagram: A force diagram, also known as a free-body diagram, is a visual representation of the forces acting on an object or system. It is a crucial tool in the analysis of Newton's Second Law of Motion, which describes the relationship between an object's acceleration and the net force acting upon it.
Free-body diagram: A free-body diagram is a graphical illustration used to visualize the forces acting on an object. It simplifies complex systems into a single object with vectors representing all external forces.
Free-Body Diagram: A free-body diagram is a visual representation of the forces acting on an object or a system in a given situation. It is a crucial tool used in the study of mechanics and the application of Newton's laws of motion, as it helps to identify and analyze the forces that influence the motion or equilibrium of a body or system.
Free-fall: Free-fall is the motion of an object under the influence of gravitational force only, without any air resistance. In this state, the object accelerates downward at a constant rate due to gravity.
Friction: Friction is the resistive force that occurs when two surfaces interact, opposing the relative motion between them. It acts parallel to the surfaces in contact and can be either static or kinetic.
Impulse: Impulse is the product of the average force applied to an object and the time duration over which it is applied. It is also equal to the change in momentum of the object.
Impulse: Impulse is a vector quantity that represents the change in momentum experienced by an object over a given time interval. It is the product of the force acting on an object and the time interval over which that force is applied.
Inertia: Inertia is the resistance of an object to any change in its state of motion. It is directly proportional to the mass of the object.
Inertia: Inertia is the tendency of an object to resist changes in its state of motion. It is a fundamental property of matter that describes an object's resistance to changes in its velocity or direction of motion.
Isolated system: An isolated system is a physical system with no external forces acting on it, meaning its total momentum remains constant. It is a key concept in studying collisions and conservation of momentum.
Mass: Mass is a fundamental property of matter that represents the amount of material in an object. It is a measure of the object's resistance to changes in its motion, and it is a scalar quantity, meaning it has magnitude but no direction. Mass is a crucial concept in physics, as it is a key factor in determining an object's behavior under the influence of forces.
Momentum: Momentum is a vector quantity that represents the product of an object's mass and velocity. It is a measure of an object's quantity of motion and is conserved in a closed system, meaning the total momentum of a system remains constant unless acted upon by an external force.
Net external force: Net external force is the vector sum of all the forces acting on a system from outside the system. It determines the acceleration of the system according to Newton's Second Law of Motion.
Net Force: Net force is the vector sum of all the individual forces acting on an object. It represents the overall force that determines the object's acceleration or lack thereof, in accordance with Newton's laws of motion.
Newton's First Law of Motion: Newton's First Law of Motion, also known as the Law of Inertia, states that an object at rest will remain at rest, and an object in motion will continue moving at a constant velocity, unless acted upon by an unbalanced force. This fundamental law describes the relationship between an object's state of motion and the forces acting upon it.
Newton's Second Law: Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. This law describes the relationship between an object's motion and the forces acting upon it, providing a fundamental principle for understanding the dynamics of physical systems.
Newton's Third Law of Motion: Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. It describes the relationship between the forces exerted by two interacting objects on each other, emphasizing that these forces are always equal in magnitude and opposite in direction.
Normal force: The normal force is the perpendicular contact force exerted by a surface on an object resting on it. It counteracts the weight of the object.
Normal Force: The normal force is a contact force that acts perpendicular to the surface of an object in response to an external force pressing the object against the surface. It is a fundamental concept in classical mechanics, particularly in the study of Newton's laws of motion.
System: A system is a defined collection of objects considered for analysis. It separates the objects of interest from the environment to study forces and motion.
System: A system is a set of interconnected elements that work together to perform a specific function or achieve a desired outcome. It is a fundamental concept in various fields, including physics, engineering, and systems theory, that helps us understand and analyze complex phenomena by breaking them down into manageable components.
Tension: Tension is the force transmitted through a string, rope, cable, or similar object when it is pulled tight by forces acting from opposite ends. This concept is crucial in understanding how forces interact in various systems, as it provides insights into how objects transmit forces and maintain equilibrium.
Vector Analysis: Vector analysis is a branch of mathematics that deals with the study of vectors, their properties, and their applications in various fields, including physics. Vectors are mathematical entities that have both magnitude and direction, and vector analysis provides the tools to manipulate and analyze these quantities in the context of physical systems.
Weight: Weight is the force exerted on an object due to gravity. It is calculated as the product of mass and gravitational acceleration.
Weight: Weight is the force exerted on an object due to gravity, calculated as the product of the object's mass and the acceleration due to gravity. This force is dependent on both the mass of the object and the gravitational field strength where the object is located. Understanding weight is crucial for analyzing motion, forces acting on objects, and buoyancy in fluids.