#### Archived

This topic is now archived and is closed to further replies.

# F = M*A

This topic is 5089 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

In this equation F = M * A A = F / M A is given in gees? If not how can i make the conversion?

##### Share on other sites
Normally A would be in m/s^2, so to get g''s, devide by a by g.
(g is 9.8 on earth, 1.6 on the moon, etc)

##### Share on other sites
sticking with SI units

a (acceleration) is given in meters per second per second (or per second squared - same thing)
f (force) in newtons
m (mass) in kilograms

I suggest you puck up a phsics book or use google rather than ask those types of questions here and get flamed!

http://www.abdn.ac.uk/physics/bio/fin5www/sld007.htm

Mabe you mean that the acceleration is given as a multiple of g(9.81m/s^2) rather than straight meters per second per second.

pongv0.1.8.6

##### Share on other sites
So to get gees it would be

Acceleration = Force / Mass

then divide

Acceleration / 9.8?

##### Share on other sites
Yes... except for one minute factor:
g equalls anywhere from 9.6 to 10 or something like that. It''s in my physics book; it depends on where on earth you are - how far you are from the core, and the density of the material beneath you.

##### Share on other sites
well it doesn''t need to be exact lol

##### Share on other sites
F = m * a could also say someting about the acceleration of a vehicle where m is the mass of your car and a the speed it gains per second.

But when you talk about gravity ''a'' is 9.81

The formula to calculate ''g'' is:

g = G * m1*m2/r^2 where G is a constant(search on the internet for the value of it) m1 is the mass of object 1(earht or another planet) m2 the mass of your object and r the distance from the core of your planet mostly this is ''r''(radius) + h (how far you are from the surface)..

I hoped this helped you

##### Share on other sites
I thought it was F=mass * VELOCITY not acceleration...

But then again my physics sucks.

##### Share on other sites
offtopic @AP: close at least. It´s p = m * v

##### Share on other sites
quote:
Original post by Anonymous Poster
I thought it was F=mass * VELOCITY not acceleration...

But then again my physics sucks.

If you try and visualize it a bit, doing mass times velocity in no way implies anything directly about force. If there is a force that does a "push" or "pull" on an object the force that is applied will give acceleration, i.e. a velocity that is changing. For example, an 18 wheeler truck that moves at constant velocity (no acceleration) has the same amount of force as it is just sitting at rest (only true if friction and other forces such as air resistence are not computed).

Mass times velocity gives the momentum of an object. The rate of change of momentum with respect to time gives the force. Very easy to visualize with calculus:
p = m * v    d(p)    m * d(v)---- =      ---- dt         dt   F = m * a

basically, the derivative of velocity is acceleration.

EDIT: Whoops, I meant derivative with respect to time t.

[edited by - nervo on March 19, 2004 6:31:33 PM]

##### Share on other sites
dp/dx is false: you derive w.r.t time

dp/dt = F = d(m*v)/dt = dm/dt*v + m*dv/dt = dm/dt*v + m*a
and this happened to be called "force"

as mass usually doesnt change over time dm/dt = 0, thus dp/dt = F = m*a

##### Share on other sites
1 g is considered to be the gravity at sea level, so roughly 9.81 m/s^2

you get an acceleration of 2G, it''s basically roughly 20m/s^2. A sports car has an acceleration between 0.8 and 1.2 G. And if you''ve been in a Supra Twin Turbo 450 bhp, then you know 1G is still quite an experience, despite the fact that we are constantly pulled down by gravity

##### Share on other sites
quote:
Original post by Anonymous Poster
dp/dx is false: you derive w.r.t time

dp/dt = F = d(m*v)/dt = dm/dt*v + m*dv/dt = dm/dt*v + m*a
and this happened to be called "force"

as mass usually doesnt change over time dm/dt = 0, thus dp/dt = F = m*a

I fixed it, but its much simpler to just write out m * d(v)/dt instead of using the product rule since m is considered constant as you have in fact pointed out as well.