centrifugal force

Examples of centrifugal force in the following topics:

• The Coriolois Force

  • When Newton's laws are transformed to a uniformly rotating frame of reference, the Coriolis and centrifugal forces appear.
  • Both forces are proportional to the mass of the object.
  • The Coriolis force is proportional to the rotation rate, and the centrifugal force is proportional to its square.
  • These additional forces are termed inertial forces, fictitious forces, or pseudo-forces.
  • However, the observer (red dot) who is standing in the rotating/non-inertial frame of reference (lower part of the picture) sees the object as following a curved path due to the Coriolis and centrifugal forces present in this frame.

• Plasma and Serum

  • It can separated by artificially spinning or centrifuging the blood at high rotations of 3000 rpm or higher .
  • The blood cells and platelets that make up about 45 percent of the blood are separated by centrifugal forces to the bottom of a specimen tube, leaving the plasma as the upper layer.
  • The liquid components of blood called plasma (yellow section) can be separated from the erythrocytes (red section) and platelets (white section) by using a centrifuging or spinning the blood.

• Transfusions of Whole Blood

  • Centrifuge quickly separates whole blood into plasma, buffy coat, and red cells by using centrifugal force to drop the cellular components to the bottom of a container.
  • Sedimentation, in which whole blood sits overnight, causing the red blood cells and plasma to settle and slowly separate by the force of normal gravity.

• Kinematics of UCM

  • Any force or combination of forces can cause a centripetal or radial acceleration.
  • Just a few examples are the tension in the rope on a tether ball, the force of Earth's gravity on the Moon, friction between roller skates and a rink floor, a banked roadway's force on a car, and forces on the tube of a spinning centrifuge.
  • Any net force causing uniform circular motion is called a centripetal force.
  • According to Newton's second law of motion, net force is mass times acceleration.
  • Thus, the magnitude of centripetal force $F_c$ is:

• Basics of DNA Replication

  • The DNA was centrifuged at high speeds in an ultracentrifuge in a tube in which a cesium chloride density gradient had been established.
  • Under these circumstances, during the spin the DNA was pulled down the ultracentrifuge tube by centrifugal force until it arrived at the spot in the salt gradient where the DNA molecules' density matched that of the surrounding salt solution.

• Force at an Angle to Displacement

  • A force does not have to, and rarely does, act on an object parallel to the direction of motion.
  • No work is done on a body moving in a circle at constant speed while constrained by a mechanical force, such as moving at constant speed in a frictionless ideal centrifuge.
  • Since the force is acting parallel to the direction of motion, the angle is equal to zero and our total work is simply the force times the displacement in the x-direction.
  • This means that the force is equally acting in the x and y-direction!
  • Recall that both the force and direction of motion are vectors.

• Obama's Foreign Policy

  • Although a residual force of 9,800 soldiers were to remain to continue training the Afghan army, it was planned that, by 2016, all U.S. troops would have left the country, except for a small number to defend U.S. diplomatic posts.
  • Under the agreement, Iran agreed to eliminate its stockpile of medium-enriched uranium, cut its stockpile of low-enriched uranium by 98%, and reduce by about two-thirds the number of its gas centrifuges for 13 years.
  • Uranium-enrichment activities will be limited to a single facility using first-generation centrifuges for 10 years and other facilities will be converted to avoid proliferation risks.
  • The war is being fought by the Syrian Government, a loose alliance of Syrian Arab rebel groups, the Syrian Democratic Forces, Salafi jihaidst groups (including al-Nusra Front), and the Islamic State of Iraq and the Levant (ISIL, sometimes referred to as ISIS).

• Molecular Excitations

  • We have effectively ignored the possible centrifugal stretching of the molecule.
  • If one includes the centrifugal effects one finds that
  • The centrifugal stretching reduces the spacing of the angular momentum energy levels for large values of $L$, but it stiffens the spring constant of the vibrational states.

• Rotational Collisions

  • An object that has a large angular velocity ω, such as a centrifuge, also has a rather large angular momentum.

• Specimen Collection

  • Specimens are allowed to clot at room temperature and then are centrifuged.