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Calculation of G Force 
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#1
Sep905, 02:09 AM

P: 2

Hi,
I'm hoping someone can provide me with a formula to calculate the amount of G Force experienced when decelerating, based on this information : A 250cc International Superkart is travelling at 250km/h and is approaching a tight corner than can be taken at a maximum of 80km/h. The driver leaves the braking to the last possible moment, and decelerates from 250km/h to 80km/h in a distance of 80m (whilst in a straight line). How many G's has the Superkart and driver experienced ? Thanks, Chris. 


#2
Sep905, 06:37 AM

Sci Advisor
P: 5,095

It's pretty straight forward if you neglect friction and wind resistance, etc...
Note: 250 km/hr = 69.4 m/sec and 80 km/hr = 22.2 m/s [tex]V^2 = {V_o}^2 + 2*a* \Delta X[/tex] [tex](22.2 \frac{m}{sec})^2 = (69.4 \frac{m}{sec})^2 + 2 a (80 m)[/tex] [tex]4323.5 \frac{m^2}{sec^2} = 160a m[/tex] [tex]a = 27.02 \frac{m}{sec^2}[/tex] [tex]g's = \frac{a}{9.81 \frac{m}{sec^2}}[/tex] [tex]g's = 2.75 [/tex] I really hope this wasn't homework. If it was, you got a freebie. 


#3
Sep905, 07:30 PM

P: 2

Thanks for that !!
No, it wasn't homework of any sort ....... unfortunately I'm not studying Physics at all. I must look into that formula so that I understand the parameters used and their relationship. The speed into metres per second was obvious anyway, but I probably lack the basics to understand and agree with the rest of it. I can see that 4816.3  492.84 = 4323.52. I wouldn't have thought friction and wind resistance would have been a factor in G force ....... ? 2.75 G's ....... my guess before reading the answer was between 2 to 2.5 G's, based on what I've heard for a Formula One car ........ Once again, thanks for taking the time to reply !! 


#4
Oct1607, 09:38 AM

P: 3

Calculation of G Force
Hello.
I'm new on this forum so hello to everyone. I'm attempting to monitor the G Force in a vehicle whiles it's driving, does anyone have any ideas? All I have is the speed of the vehicle, would this be enough to measure the G Force? jason 


#5
Oct1607, 10:35 AM

HW Helper
P: 1,979

You have to know the acceleration. If you are moving with a constant speed on a circular track, then you have to know the radius of the track and the speed. 


#6
Oct1607, 10:41 AM

P: 3

But obviously the vehicle needs to go from 0mph to (say) 90mph,
Obviously any variation in speed will result in G Force?? Is this correct? Let's say for arguement sake, it's in s straight line? How would I work out a running G Force? i.e. Like the one on F1 (ITV) 


#7
Oct1607, 10:42 AM

P: 3

Lets expand on that.
If I made a trip from A to B, I would want to know the maximum amount of G Force I went through during this trip? Can you Help. Ta 


#8
Oct1607, 10:56 AM

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#9
Oct1607, 03:10 PM

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P: 1,979

 Hi Huttojb, You need some more parameters to find the accn or the g force. If you know the time 't', and accn is constant and the motion is in a st line, then the accn 'a' is (900)/t mph/h. If you know the dist, then too you can find the accn if it is constant. In practice, the accn is generally not constant. So you would need a detailed disttime graph; or hang a spring balance in the car to see the effective g force. (Note that the reading on the balance would include the g field of the earth.) The maximum accn would perhaps be when you start and reach a high speed in a few seconds. Or when you slow down by stepping on the brakes very hard. 


#10
Oct1607, 07:28 PM

HW Helper
P: 7,131

http://www.motec.com/products/dash/adl2dash.htm 


#11
Sep2410, 11:06 AM

P: 1

I have a Physics problem that I cant Figure out:
An Aircraft goes from 0 MPH to 85 MPH during its take off run of 800 feet in 10 seconds. The aircrafts takeoff weight is 2600 pounds and has 4 people aboard with 40 mounds of bags. What is the Gforce experienced by the People on board? ' 


#12
Sep2410, 11:40 AM

Sci Advisor
PF Gold
P: 1,473

we did a lot of posts on this on MEch engineering forum and other forum here
Centripetal force Car making a turn Jun610, 06:57 AM race car suspension class Jul2209, 11:03 AM see post below in gen pyshics forumn.. Wider tire giving better traction debate! Old Aug1509, 04:19 AM 


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