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2007-03-19 08:14:47 · 5 answers · asked by plolol 2 in Science & Mathematics Physics

5 answers

Force is equal to the derivative of linear momentum with respect to time. While force is usually defined as being equal to the product of mass and acceleration, i.e., F = ma, a more correct definition is F = dp/dt, where p is linear momentum.

The F = dp/dt definition becomes very important in special relativity. Momentum, p, is equal to the product of mass and velocity, so p = mv. At speeds much lower than the speed of light, we can say dp/dt = d/dt(mv) = m*dv/dt = ma, because mass is constant and acceleration is the time derivative of velocity. However, at speeds on the same order of magnitude as the speed of light, m is not constant but instead has a dependency on v. F = ma no longer holds true, but F = dp/dt remains valid.

2007-03-19 08:17:56 · answer #1 · answered by DavidK93 7 · 0 0

Either - the bigger the force applied, the higher the momentum.
or - the higher the linear momentum, the higher the force needed to stop.

2007-03-19 09:04:37 · answer #2 · answered by R.E.M.E. 5 · 0 0

The change of momenum of an object as the consequence of force applied to it can be found as follows:

∆p = F∆t

Compare this with the change of kinetic energy of an object:

∆E = F∆x

From this we can see that

∆E/∆p = dE/dp = ∆x/∆t = dx/dt = v

This is a general result true in classical, relativistic, and quantum mechanics, and it's even true for light, as E = pc. It's worth keeping in mind.

2007-03-19 08:40:06 · answer #3 · answered by Scythian1950 7 · 0 0

F= m a
F =m delta V/delta t
F delta V = m delta t
impuls = momentum

2007-03-19 12:15:05 · answer #4 · answered by Anonymous · 0 0

tension is rather the fee of replace of momentum with admire to time.. F= (mv-mu)/t this provides F=ma because of the fact the mass is persevering with and the differential of speed is acceleration (with admire to time)

2016-10-19 02:25:47 · answer #5 · answered by Anonymous · 0 0

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