Lecture 11 - Newton's Laws Flashcards
Who authored “Philosophiae Naturalis Principia Mathematica” and what significant contribution to physics does it contain?
Sir Isaac Newton authored “Philosophiae Naturalis Principia Mathematica,” which contains significant contributions to physics, including the formulation of the Three Laws of Motion.
What does the Law of Inertia (Law #1) state about the motion of a body?
The Law of Inertia states that a body will maintain a state of rest or constant velocity unless acted upon by an external force that changes its state. Inertia represents a resistance to acceleration, indicating how hard it is to change the velocity of an object.
According to the Law of Acceleration/Momentum (Law #2), how does the magnitude of acceleration change with the applied force?
According to the Law of Acceleration/Momentum, the magnitude of acceleration of a body is directly proportional to the force applied to it and inversely proportional to the body’s mass.
This means if the applied force is increased, acceleration increases, and if the force is reduced, acceleration decreases, maintaining a proportional relationship.
What happens to the velocity of a body if the applied force is reduced by 50%, based on Law #2?
If the applied force is reduced by 50%, the acceleration is reduced by 50% according to Law #2. The change in velocity depends on the initial velocity and direction; velocity may increase or decrease depending on these factors, as velocity is influenced by the direction and magnitude of acceleration, not directly by the force.
What principle is described by the Law of Reaction (Law #3)?
The Law of Reaction states that for every action, there is an equal and opposite reaction. This means when one body exerts a force on a second body, the second body exerts a reaction that is equal in magnitude and opposite in direction on the first body. An example of this is the ground reaction force, where the ground pushes up on our body with a force equal in magnitude and opposite in direction to the force we exert on the ground.
How does inertia affect the acceleration of a body according to Law #1?
Inertia affects the acceleration of a body by representing the body’s resistance to any change in its state of motion. The greater the inertia (mass) of a body, the harder it is to accelerate the body. This resistance to acceleration means that more force is required to change the motion of a body with high inertia compared to one with low inertia.
In the context of Law #2, what would be the effect on a body’s acceleration if its mass is doubled while the applied force remains constant?
If the mass of a body is doubled while the applied force remains constant, the body’s acceleration will be halved. This is because acceleration is inversely proportional to the mass of the body, as described by the equation F = ma. Doubling the mass with the same force results in a reduction of acceleration by a factor of two.
Can you provide an example of the Law of Reaction (Law #3) from sports?
An example of the Law of Reaction from sports is a swimmer pushing off the wall of a pool. When the swimmer pushes against the wall, the wall exerts an equal and opposite force on the swimmer, propelling them forward through the water. This action-reaction pair illustrates how forces operate in pairs and how the reaction force aids in the swimmer’s movement.
What is a Free Body Diagram?
A Free Body Diagram is a sketch that shows a defined system in isolation with all of the force vectors and, if applicable, torque vectors acting on the system. It visually represents the forces external to the system, illustrating their direction and point of application.
What is the primary purpose of a Free Body Diagram?
The primary purpose of a Free Body Diagram is to provide a pictorial representation of the forces acting on a system, specifically illustrating the left side of Newton’s 2nd Law of Motion (F = ma).
It helps in understanding and analyzing the forces and torques external to the system by showing their lines of action and points of application.
How does a Free Body Diagram relate to Newton’s Second Law of Motion?
A Free Body Diagram relates to Newton’s Second Law of Motion by visually representing all external forces acting on a system, which are essential for calculating the system’s acceleration (a) given its mass (m). It effectively illustrates the equation F = ma, where F is the sum of all external forces on the system.
Why is it important to draw the line of action and point of application in a Free Body Diagram?
Drawing the line of action and point of application in a Free Body Diagram is important because it provides precise information on how each force (and torque, if applicable) acts upon the system.
This detail helps in accurately analyzing the effects of these forces on the system’s motion or equilibrium, including understanding how they contribute to translational and rotational acceleration.
