force

Examples of force in the following topics:

• Forces in Two Dimensions

  • For example, when determining what happens when two forces act on the same object, it is necessary to know both the magnitude and the direction of both forces to calculate the result.
  • In this simple one-dimensional example, without knowing the direction of the forces it is impossible to decide whether the net force is the result of adding the two force magnitudes or subtracting one from the other.
  • Associating forces with vectors avoids such problems.
  • Ideally, these diagrams are drawn with the angles and relative magnitudes of the force vectors preserved so that graphical vector addition can be done to determine the net force.
  • Forces are resolved and added together to determine their magnitudes and the net force.

• Problem-Solving With Friction and Inclines

  • Recall that the force of friction depends on both the coefficient of friction and the normal force.
  • As always, the frictional force resists motion.
  • If the frictional force is equal to the gravitational force the block will not slide down the incline.
  • If the maximum frictional force is greater than the force of gravity, the sum of the forces is still 0.
  • The force of friction can never exceed the other forces acting on it.

• Normal Forces

  • The normal force comes about when an object contacts a surface; the resulting force is always perpendicular to the surface of contact.
  • The person remains still because the forces due to weight and the normal force create a net force of zero on the person.
  • When the elevator goes up, the normal force is actually greater than the force due to gravity.
  • The second is the normal force.
  • The following forces act on the mass: the weight of the mass ($m \cdot g$),the force due to friction ($F_r$),and the normal force ($F_n$).

• Centripetal Force

  • A force which causes motion in a curved path is called a centripetal force (uniform circular motion is an example of centripetal force).
  • A force that causes motion in a curved path is called a centripetal force.
  • Uniform circular motion is an example of centripetal force in action.
  • Centripetal force can also be expressed in terms of angular velocity.
  • The equation for centripetal force using angular velocity is:

• Dispersion Force

  • These intermolecular forces are also sometimes called "induced dipole-induced dipole" or "momentary dipole" forces.
  • London dispersion forces are part of the van der Waals forces, or weak intermolecular attractions.
  • Van der Waals forces help explain how nitrogen can be liquefied.
  • London dispersion forces allow otherwise non-polar molecules to have attractive forces.
  • There are two kinds of attractive forces shown in this model: Coulomb forces (the attraction between ions) and Van der Waals forces (an additional attractive force between all atoms).

• Ion-Dipole Force

  • The ion-dipole force is an intermolecular attraction between an ion and a polar molecule.
  • However, ion-dipole forces involve ions instead of solely polar molecules.
  • Ion-dipole forces are stronger than dipole interactions because the charge of any ion is much greater than the charge of a dipole; the strength of the ion-dipole force is proportionate to ion charge.
  • An ion-induced dipole force occurs when an ion interacts with a non-polar molecule.
  • Ion-dipole forces are generated between polar water molecules and a sodium ion.

• Impulse

  • Impulse, or change in momentum, equals the average net external force multiplied by the time this force acts.
  • where F is the net force on the system, and Δt is the duration of the force.
  • change in momentum equals the average net external force multiplied by the time this force acts.
  • Forces are usually not constant.
  • A graph of force versus time with time along the x-axis and force along the y-axis for an actual force and an equivalent effective force.

• Binding Energy and Nuclear Forces

  • Nuclear force is the force that is responsible for binding of protons and neutrons into atomic nuclei.
  • The nuclear force is the force between two or more component parts of an atomic nuclei.
  • The nuclear force is now understood as a residual effect of an even more powerful "strong force" or strong interaction.
  • The nuclear forces arising between nucleons are now seen as analogous to the forces in chemistry between neutral atoms or molecules (called London forces).
  • These nuclear forces are very weak compared to direct gluon forces ("color forces" or "strong forces") inside nucleons, and the nuclear forces extend over only a few nuclear diameters, falling exponentially with distance.

• Applications of Newton's Laws

  • Net force affects the motion, postion and/or shape of objects (some important and commonly used forces are friction, drag and deformation).
  • Another interesting force in everyday life is the force of drag on an object when it is moving in a fluid (either gas or liquid).
  • Like friction, the force of drag is a force that resists motion.
  • We see an illustrated example of drag force in.
  • It omits the two vertical forces—the weight of the barge and the buoyant force of the water supporting it cancel and are not shown.

• Simple Machines

  • A simple machine has an applied force that works against a load force.
  • The ratio of the output force to the input force is the mechanical advantage of the machine.
  • They use only three forces: the input force, output force, and force on the pivot.
  • The amount of force produced by a machine can not be greater than the amount of force put into it.
  • Develop an understanding of how a machine applies force to work against a load force