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From: GregS on 16 Apr 2007 09:36
I need some assistance to figure out a problem. i was looking for an online calculator.
I have a weigth mass, and I want to drop it at different heights, and compute
the impact force. The impact area would also affect the actual force.
Its about a 1 lb weight and a drop of 4 to 10 inches. I was planning on buying
a load cell of 100 lbs capacity to try to measure this, and I wanted to know if this
was enough.

greg
From: Sam Wormley on 16 Apr 2007 09:45
GregS wrote:
> I need some assistance to figure out a problem. i was looking for an online calculator.
> I have a weigth mass, and I want to drop it at different heights, and compute
> the impact force. The impact area would also affect the actual force.
> Its about a 1 lb weight and a drop of 4 to 10 inches. I was planning on buying
> a load cell of 100 lbs capacity to try to measure this, and I wanted to know if this
> was enough.
>
> greg


Try: http://hyperphysics.phy-astr.gsu.edu/hbase/impulse.html
From: GregS on 16 Apr 2007 10:33
In article <86LUh.58733$oV.58014(a)attbi_s21>, Sam Wormley <swormley1(a)mchsi.com> wrote:
>GregS wrote:
>> I need some assistance to figure out a problem. i was looking for an online
> calculator.
>> I have a weigth mass, and I want to drop it at different heights, and compute
>> the impact force. The impact area would also affect the actual force.
>> Its about a 1 lb weight and a drop of 4 to 10 inches. I was planning on
> buying
>> a load cell of 100 lbs capacity to try to measure this, and I wanted to know
> if this
>> was enough.
>>
>> greg
>
>
> Try: http://hyperphysics.phy-astr.gsu.edu/hbase/impulse.html

I have distance, but velocity is ????

greg
From: JWS on 16 Apr 2007 10:39
GregS wrote:

> I need some assistance to figure out a problem. i was looking
> for an online calculator. I have a weigth mass, and I want to
> drop it at different heights, and compute the impact force. The
> impact area would also affect the actual force. Its about a 1
> lb weight and a drop of 4 to 10 inches. I was planning on
> buying a load cell of 100 lbs capacity to try to measure this,
> and I wanted to know if this was enough.

> greg

The formula is

F_dynamic t_fall
--------- = 1 + -------
F_static t_sound

in which

F_dynamic = impact force
F_static = force between the ground and the weight, when
the weight is just lying on the ground
t_fall = the fall time of the weight (= sqrt(2h/g))
t_sound = the time in which a sound wave runs through
the weight, or L/v (L="height" of weight, v =
speed of sound). Speed of sound in solids can be
looked up in tables; e.g. in steel, 5000 m/sec.

This assumes that your load cell is infinitely stiff, i.e., it
does not act as some kind of cushion which absorbs energy from the
fall, thereby reducing the impact force. I think that measuring
impact forces is quite a challenge for experimenters. I'd be very
interested in your results. See http://www.jw-stumpel.nl/bounce.html
From: Uncle Al on 16 Apr 2007 10:52
GregS wrote:
>
> In article <86LUh.58733$oV.58014(a)attbi_s21>, Sam Wormley <swormley1(a)mchsi.com> wrote:
> >GregS wrote:
> >> I need some assistance to figure out a problem. i was looking for an online
> > calculator.
> >> I have a weigth mass, and I want to drop it at different heights, and compute
> >> the impact force. The impact area would also affect the actual force.
> >> Its about a 1 lb weight and a drop of 4 to 10 inches. I was planning on
> > buying
> >> a load cell of 100 lbs capacity to try to measure this, and I wanted to know
> > if this
> >> was enough.
> >>
> >> greg
> >
> >
> > Try: http://hyperphysics.phy-astr.gsu.edu/hbase/impulse.html
>
> I have distance, but velocity is ????

s = (at^2)/2
v = at

a = one gee, corrected for your latitude and altitude above the geoid.

g =
(978.032677)[1+(0.00193185139)sin^2(lat)]/sqrt[1-(0.00669437999)sin^2(lat)]
cm/sec^2
dg/dh = 0.000308766[1-(0.0014665)sin^2(lat)] cm/sec^2-meter

r = geocentric radius
a = free fall acceleration
lat = latitude
g = gravitational acceleration
h = altitude above sea level
s = distance
t = time
v = velocity

You can add the ballistic coefficient if you want to trim decimal
places. Since your mass is dense, your medium is not viscous, and
your fall time is short, Stokes won't get you and you are nowhere near
terminal velocity.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2
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