force

(noun)

a physical quantity that denotes ability to push, pull, twist or accelerate a body which is measured in a unit dimensioned in $\frac{M \cdot L}{T^2}$ (SI: newton, abbreviated N; CGS: dyne, abbreviated dyn)

Related Terms

Examples of force in the following topics:

  • Physics and Engineering: Fluid Pressure and Force

    • Pressure ($p$) is force per unit area applied in a direction perpendicular to the surface of an object.
    • It relates the vector surface element (a vector normal to the surface) with the normal force acting on it.
    • The total force normal to the contact surface would be:
    • Using this expression, we can calculate the total force that the fluid pressure gives rise to:
    • This equation, for example, can be used to calculate the total force on a submarine submerged in the sea.

  • Work

    • Forces may do work on a system.
    • For moving objects, the rate of the work done by a force (measured in joules/second, or watts) is the scalar product of the force (a vector) and the velocity vector of the point of application.
    • This scalar product of force and velocity is classified as instantaneous power delivered by the force.
    • Work is the result of a force on a point that moves through a distance.
    • If the force is always directed along this line, and the magnitude of the force is $F$, then this integral simplifies to:

  • Applications of Second-Order Differential Equations

    • In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force, $F$, proportional to the displacement, $x$: $\vec F = -k \vec x \,$, where $k$ is a positive constant.
    • If $F$ is the only force acting on the system, the system is called a simple harmonic oscillator, and it undergoes simple harmonic motion: sinusoidal oscillations about the equilibrium point, with a constant amplitude and a constant frequency.
    • In many vibrating systems the frictional force $Ff$ can be modeled as being proportional to the velocity v of the object: $Ff = −cv$, where $c$ is called the viscous damping coefficient.
    • Driven harmonic oscillator: Driven harmonic oscillators are damped oscillators further affected by an externally applied force $F(t)$.

  • Fundamental Theorem for Line Integrals

    • In physics this theorem is one of the ways of defining a "conservative force."
    • Work done by conservative forces does not depend on the path followed by the object, but only the end points, as the above equation shows.
    • Therefore, electric force is a conservative force.

  • Vector Fields

    • Vector fields are often used to model the speed and direction of a moving fluid throughout space, for example, or the strength and direction of some force, such as the magnetic or gravitational force, as it changes from point to point.
    • When a vector field represents force, the line integral of a vector field represents the work done by a force moving along a path, and, under this interpretation, conservation of energy is exhibited as a special case of the fundamental theorem of calculus.

  • Planetary Motion According to Kepler and Newton

    • From this, Newton defined the force acting on a planet as the product of its mass and acceleration.
    • Therefore, by Newton's law, every planet is attracted to the Sun, and the force acting on a planet is directly proportional to the mass and inversely proportional to the square of its distance from the Sun.
    • The green arrow represents the planet's velocity, and the purple arrows represent the force on the planet.

  • Vectors in Three Dimensions

    • Vectors play an important role in physics: velocity and acceleration of a moving object and forces acting on it are all described by vectors.

  • Differentiation and Rates of Change in the Natural and Social Sciences

    • Newton's second law of motion states that the derivative of the momentum of a body equals the force applied to the body.

  • The Divergence Theorem

  • Numerical Integration

    • A 'brute force' kind of numerical integration can be done, if the integrand is reasonably well-behaved (i.e. piecewise continuous and of bounded variation), by evaluating the integrand with very small increments.