# Question #f23b2

Sep 23, 2014

Put simply, a force is something which changes the momentum of an object. The magnitude of a force is the rate of change of momentum caused.

This is shown by manipulation of the famous equation $F = m a$

$F = m a = m \frac{{v}_{f} - {v}_{i}}{t} = \frac{{p}_{f} - {p}_{i}}{t}$

Where $F$ is the force
$m$ is the mass of the object
$a$ is acceleration, which is the rate of change of velocity
${v}_{i}$ is the initial velocity of the object which the force acts upon
${v}_{f}$ is the object's final velocity
$t$ is time
$p$ is momentum, which is equal to $m \times v$

Extra info:
Of course, because force is the rate of change of momentum, it can be linked to an object whose mass changes while velocity remains constant.

$F = \frac{{p}_{f} - {p}_{i}}{t} = v \frac{{m}_{f} - {m}_{i}}{t}$

Where ${m}_{f}$ is final mass and ${m}_{i}$ is initial mass.

Force can also be related to an object whose mass and velocity change simultaneously, but those equations involve calculus, so I won't include those here.

Mar 28, 2015

In physics, a force is any interaction which tends to change the motion of an object. In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described by intuitive concepts such as a push or a pull.