[Thoran]

Originally posted by Sir Krustin: quote: Originally posted by Malthaussen: I'll agree with you there, SG, but I do have to ask Ilander why he persists in discussing physics without showing the relevant equation. According to my ancient textbook, it is f = mv2. -- Mal

Dimensionally, Force is typically represented in units of kg*m/second squared Note that if it was mass times velocity squared, then the units of what you term "force" would be kg*meters sqaured/seconds squared

He's already spelled it out for you.

mass = kg
v^2 = m^2/sec^2

therefore f = mv^2
f = (kg) * (m^2/sec^2)
f = (kg*m*m)/(sec*sec) not kg*m/sec*sec [/QUOTE]I have not paid attention to the 'formula debate' sideline of the thread, but your above forumla is incorrect.

Units for Position : meters

Velocity is the first derivative of position over time (typically represented as dx/dt) which has metric units of: m/s

Acceleration is the second derivitave of position of time (d^2x/dt^2), or the first derivative of velocity over time (dv/dt)
Units for Acceleration : meters per second squared (m/s^2)

Force = mass (kg) * acceleration (m/s^2) so units for force are kg*m/s^2

EDIT AFTER REVIEWING THE PHYSICS SIDELINE: Malthaussen the textbook you're quoting has a typo... happens all the time. As Scotty would say, "You cannot change the laws of physics Jim!"

You could calculate average force if you have mass, starting and ending velocities and the amount of time elapsed. The formula would look something like this:

Force = mass * (final velocity - starting velocity) / (elapsed time)

note that this is just another way of saying F = mass * dv/dt = mass * accel.

I'm still not exacly sure why this is relevant to the topic. If you're talking about blade force applied when striking an object than you'd LOTS of information to use this equation (either that or you'd need to make a lot of assumptions).

[ 12-09-2004, 12:58 PM: Message edited by: Thoran ]