| Topic: |
Science > Physics |
| User: |
"Ralph Smith" |
| Date: |
18 Sep 2005 09:05:51 AM |
| Object: |
Need to know a physical constant. |
I know that force = power / speed in general and that
pounds = 375.0 * (hp / mph).
I need to know what the constant is for the metric system:
newtons = K * (watts / kph).
Does anyone know what K is?
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| User: "John C. Polasek" |
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| Title: Re: Need to know a physical constant. |
18 Sep 2005 10:53:29 AM |
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On Sun, 18 Sep 2005 10:05:51 -0400, Ralph Smith <ralph@lkjlkj.com>
wrote:
I know that force = power / speed in general and that
pounds = 375.0 * (hp / mph).
I need to know what the constant is for the metric system:
newtons = K * (watts / kph).
Does anyone know what K is?
It's 0.278
John Polasek
http://www.dualspace.net
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| User: "Brit" |
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| Title: Re: Need to know a physical constant. |
18 Sep 2005 10:42:48 AM |
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Ralph Smith wrote:
I know that force = power / speed in general and that
pounds = 375.0 * (hp / mph).
I need to know what the constant is for the metric system:
newtons = K * (watts / kph).
Does anyone know what K is?
1/3.6 or 0.2778 approx.
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| User: "Ralph Smith" |
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| Title: Re: Need to know a physical constant. |
18 Sep 2005 11:38:02 AM |
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On 18 Sep 2005 08:42:48 -0700, "Brit" <pete@wild-grant.net> wrote:
Ralph Smith wrote:
I know that force = power / speed in general and that
pounds = 375.0 * (hp / mph).
I need to know what the constant is for the metric system:
newtons = K * (watts / kph).
Does anyone know what K is?
1/3.6 or 0.2778 approx.
thanks for the number. Can someone tell me how it is derived? Eg,
375.0 = 33000 / (5280/60)
Where does the 3.6 come from?
Ralph
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| User: "CWatters" |
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| Title: Re: Need to know a physical constant. |
18 Sep 2005 12:14:20 PM |
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In metric iit's better to use
P = F*V
where
P is in Watts
F is in Newtons
V is in Meters per Second
Then convert to kilometers per hour if you really must.
Where does the 3.6 come from?
Hint : How many seconds in an hour?
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| User: "Martin" |
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| Title: Re: Need to know a physical constant. |
19 Sep 2005 05:40:20 AM |
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CWatters wrote:
In metric iit's better to use
P = F*V
where
P is in Watts
F is in Newtons
V is in Meters per Second
Then convert to kilometers per hour if you really must.
Where does the 3.6 come from?
Hint : How many seconds in an hour?
This has to be a 12YO's home work question
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| User: "CWatters" |
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| Title: Re: Need to know a physical constant. |
19 Sep 2005 09:43:41 AM |
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"Martin" <usenet@etiqa.co.uk> wrote in message
news:432e9585$0$25428$db0fefd9@news.zen.co.uk...
CWatters wrote:
In metric iit's better to use
P = F*V
where
P is in Watts
F is in Newtons
V is in Meters per Second
Then convert to kilometers per hour if you really must.
Where does the 3.6 come from?
Hint : How many seconds in an hour?
This has to be a 12YO's home work question
Probably. It sounds like it was set by someone who doesn't like the metric
system. They appear to be making it look more complicated that it really is.
He isn't actually looking for a physical constant - just correction factor
for using non-standard units.
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| User: "John C. Polasek" |
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| Title: Re: Need to know a physical constant. |
19 Sep 2005 04:19:59 PM |
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On Sun, 18 Sep 2005 12:38:02 -0400, Ralph Smith <ralph@lkjlkj.com>
wrote:
On 18 Sep 2005 08:42:48 -0700, "Brit" <pete@wild-grant.net> wrote:
Ralph Smith wrote:
I know that force = power / speed in general and that
pounds = 375.0 * (hp / mph).
I need to know what the constant is for the metric system:
newtons = K * (watts / kph).
Does anyone know what K is?
1/3.6 or 0.2778 approx.
thanks for the number. Can someone tell me how it is derived? Eg,
375.0 = 33000 / (5280/60)
Where does the 3.6 come from?
Ralph
OK I worked it out for you. 1W = 1 N*m/sec = 1 Nm/s
N = K W/Kph
K = N*Kph/W
Numerator for K: N*1000*m/3600sec
Denominator W = N*m/sec
K = 1000/3600
John Polasek
http://www.dualspace.net
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