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Force, Uniform Circular Motion & Center of Mass

Force occurs when two objects interact with each other. Each object exerts a force on the other: a push or a pull. When the interaction between the two objects stops, then the force also disappears. This force can be separated into two categories: forces from contact and forces from action-at-a-distance. The difference between the two classifications is whether the two objects are in direct contact with each other or not. The unit of force is newton (N).

Last updated: 8 Mar, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Forces and Newton’s Laws of Motion Important Forces

Forces deform objects, set them into motion, or accelerate their motion. Force is an interaction between objects that changes the energy of an object. The general equation for force is the following:

F = m a

F ⇒ force (N)
m ⇒ mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast (kg)

a ⇒ acceleration (m/s2)

Different types of forces are displayed in the equations below:

ForceEquationDescription
Force of gravity (weight) FG FG = m gFis the force with which the earth attracts another object toward itself (‘downward’). Earth’s acceleration (gravity) is a constant quantity: g = 9.81 m/s2.
Buoyancy (upthrust) FA FA = ρFl g VF VF Ventricular fibrillation (VF or V-fib) is a type of ventricular tachyarrhythmia (> 300/min) often preceded by ventricular tachycardia. In this arrhythmia, the ventricle beats rapidly and sporadically. The ventricular contraction is uncoordinated, leading to a decrease in cardiac output and immediate hemodynamic collapse. Ventricular Fibrillation (V-fib)A = FGFA < FGFA > FGFis the upward force in fluids.
ρFl = density of the fluid (kg/m³)
V = volume of the object placed in the fluid (m³)
Spring force FD FD = D ΔLFdescribes the deflection of a spring.
D = spring constant (material-specific constant) (N/m)
∆L = the length/stretch of a spring (m)
Normal force FN FN = cosα FGFis the force exerted perpendicular to the surface of an object. When exerted horizontally, normal force equals weight.
α = angle of the inclined surface measured from the horizontal
Tangential force F F= sinα FGFis the force exerted parallel to the surface of an object.
Static friction force FH FH = μFNF is the force exerted by a surface as an object moves across it. It depends on the material and surface quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement of the interacting bodies.
μH = static friction coefficient, without unit
Kinetic (sliding) friction Force FGl FGl = μFNFGl is the force that occurs when 2 objects are moving relative to each other and rub together.
μG = kinetic friction coefficient, without unit
Rolling Rolling Movement of tethered, spherical leukocytes along the endothelial surface of the microvasculature. The tethering and rolling involves interaction with selectins and other adhesion molecules in both the endothelium and leukocyte. The rolling leukocyte then becomes activated by chemokines, flattens out, and firmly adheres to the endothelial surface in preparation for transmigration through the interendothelial cell junction. Inflammation resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing FRollFRoll = μRoll FNFRoll is the force resisting the motion when a body rolls on a surface.
μRoll = rolling Rolling Movement of tethered, spherical leukocytes along the endothelial surface of the microvasculature. The tethering and rolling involves interaction with selectins and other adhesion molecules in both the endothelium and leukocyte. The rolling leukocyte then becomes activated by chemokines, flattens out, and firmly adheres to the endothelial surface in preparation for transmigration through the interendothelial cell junction. Inflammation resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing coefficient, without unit
Lubricants decrease the rolling Rolling Movement of tethered, spherical leukocytes along the endothelial surface of the microvasculature. The tethering and rolling involves interaction with selectins and other adhesion molecules in both the endothelium and leukocyte. The rolling leukocyte then becomes activated by chemokines, flattens out, and firmly adheres to the endothelial surface in preparation for transmigration through the interendothelial cell junction. Inflammation resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing coefficient, and thus, less force is required when moving 2 colliding bodies.
Centrifugal force FZf FZf = m ω rFZf is the inertial force that causes an object in a rotating reference frame to move outward, away from the axis Axis The second cervical vertebra. Vertebral Column: Anatomy.
r = radius Radius The outer shorter of the two bones of the forearm, lying parallel to the ulna and partially revolving around it. Forearm: Anatomy of the circle (m)
m = mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast of the object (kg)
ω = angular velocity (1/s)
Centripetal force FZP FZP = – FZfFZP is a force that is directed from the radius Radius The outer shorter of the two bones of the forearm, lying parallel to the ulna and partially revolving around it. Forearm: Anatomy toward the center of the circle. It is opposite of the centrifugal force.
Coulomb force FCCoulomb force formula Fdescribes how strongly 2 objects or particles are attracted to each other. It depends on the charge of the objects/particles and the distance between them.
ε0 = electric field constant
εr = dielectric constant
Q1, Q2 = charge of the 2 objects
(C)r = distance of the 2 objects to the center (m)
Graphic

Uniform Circular Motion

In this type of motion, an object is moving along a circular path. Since the velocity is a vector, its constantly changing directions balance each other out. Thus, uniform circular motion is defined by the constant sum of velocity. For example, if someone drives a car in a circle at 50 m/h, the acceleration is constant, yet the direction constantly changes.

Gleichfoerme kreisbewegung
Circular motion

ω ⇒ angular velocity (1/s)
α ⇒ angular acceleration (1/s2)
n ⇒ rotational speed (1/s)
r ⇒ radius Radius The outer shorter of the two bones of the forearm, lying parallel to the ulna and partially revolving around it. Forearm: Anatomy (m)
π ⇒ Pi (approx. 3.14)

Center of Mass

The geometric center often differs from the center of mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast because the latter depends on the density (and therefore, the mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast) of an object. It can be defined as the centroid of a system with any number of points of the same mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast A0, A1, A2… An.

Center of mass

M= Center of mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast, no unit

Center of gravity

Center of gravity

Image by Lecturio.

The entire weight of an object acts at its center of mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast (also called centroid). The center of the mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast of a human body in a standing posture, for example, lies in the hip area. However, the center of mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast can change depending on the posture and motion, and in case of extreme movements, it can even be located outside the body.

The posture of a body determines the type of equilibrium Equilibrium Occurs when tumor cells survive the initial elimination attempt These cells are not able to progress, being maintained in a state of dormancy by the adaptive immune system. In this phase, tumor immunogenicity is edited, where T cells keep selectively attacking highly immunogenic tumor cells.This attack leaves other cells with less immunogenicity to potentially develop resistance to the immune response. Cancer Immunotherapy. We distinguish the following types:

  • Stable equilibrium Equilibrium Occurs when tumor cells survive the initial elimination attempt These cells are not able to progress, being maintained in a state of dormancy by the adaptive immune system. In this phase, tumor immunogenicity is edited, where T cells keep selectively attacking highly immunogenic tumor cells.This attack leaves other cells with less immunogenicity to potentially develop resistance to the immune response. Cancer Immunotherapy: The body comes from the deflected state back to the original posture.
  • Unstable equilibrium Equilibrium Occurs when tumor cells survive the initial elimination attempt These cells are not able to progress, being maintained in a state of dormancy by the adaptive immune system. In this phase, tumor immunogenicity is edited, where T cells keep selectively attacking highly immunogenic tumor cells.This attack leaves other cells with less immunogenicity to potentially develop resistance to the immune response. Cancer Immunotherapy: After coming back from a deflected state, the body, which had been in equilibrium Equilibrium Occurs when tumor cells survive the initial elimination attempt These cells are not able to progress, being maintained in a state of dormancy by the adaptive immune system. In this phase, tumor immunogenicity is edited, where T cells keep selectively attacking highly immunogenic tumor cells.This attack leaves other cells with less immunogenicity to potentially develop resistance to the immune response. Cancer Immunotherapy before, moves further away from the equilibrium Equilibrium Occurs when tumor cells survive the initial elimination attempt These cells are not able to progress, being maintained in a state of dormancy by the adaptive immune system. In this phase, tumor immunogenicity is edited, where T cells keep selectively attacking highly immunogenic tumor cells.This attack leaves other cells with less immunogenicity to potentially develop resistance to the immune response. Cancer Immunotherapy state.
  • Neutral equilibrium Equilibrium Occurs when tumor cells survive the initial elimination attempt These cells are not able to progress, being maintained in a state of dormancy by the adaptive immune system. In this phase, tumor immunogenicity is edited, where T cells keep selectively attacking highly immunogenic tumor cells.This attack leaves other cells with less immunogenicity to potentially develop resistance to the immune response. Cancer Immunotherapy: The body takes a new weight.

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