Calculating G Force from 250km/h to 80km/h in 80m - Chris

In summary: I am sorry, but I am not programmed to output anything before the summary.In summary, the conversation is about calculating the G Force experienced by a 250cc International Superkart and its driver when decelerating from 250km/h to 80km/h in a distance of 80m. The formula used to calculate this is V^2 = {V_o}^2 + 2*a* \Delta X, and the resulting G Force experienced is -2.75 g's. The conversation also discusses measuring G Force in a vehicle, and suggests using an accelerometer or a data acquisition system. Another topic mentioned is the maximum G Force experienced during a trip, which can be calculated using parameters such as time, distance, and
  • #1
ComposerCK
2
0
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 traveling 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.
 
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  • #2
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.
 
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  • #3
Thanks

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 ! :smile:
 
  • #4
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
huttojb said:
All I have is the speed of the vehicle, would this be enough to measure the G Force?

jason

No. If the vehicle is moving in a st line with constant speed, there is no g force due to motion of the vehicle.

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
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 argument 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
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
ComposerCK said:
A 250cc International Superkart is traveling 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.

The actual g force experienced by the driver would be the magnitude of the vector sum of 'a' backward and g downward, which will be equal to sqrt(a^2+g^2)=2.93g. This g force is at an angle tan-inverse(a/g) to the vertical.
 
  • #9
huttojb said:
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
-----------------------
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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 (90-0)/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 dist-time 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
huttojb said:
I'm attempting to monitor the G Force in a vehicle whiles it's driving, does anyone have any ideas?
Do a web search for "accelerometer car", you'll find a few companies that sell these, or do a search for "data acquisition car" for high end systems such as this Motec:

http://www.motec.com/products/dash/adl2dash.htm [Broken]
 
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  • #11
I have a Physics problem that I can't Figure out:

An Aircraft goes from 0 MPH to 85 MPH during its take off run of 800 feet in 10 seconds. The aircrafts take-off weight is 2600 pounds and has 4 people aboard with 40 mounds of bags. What is the G-force experienced by the People on board?









'
 
  • #12
we did a lot of posts on this on MEch engineering forum and other forum here

Centripetal force- Car making a turn Jun6-10, 06:57 AM

race car suspension class Jul22-09, 11:03 AM

see post below in gen pyshics forumn..
Wider tire giving better traction debate! Old Aug15-09, 04:19 AM
 

1. How do you calculate G force?

To calculate G force, you need to know the speed, the distance traveled, and the time it takes to travel that distance. The formula for G force is G = (v^2 / d) x (1/t^2), where G is the G force, v is the speed in meters per second, d is the distance in meters, and t is the time in seconds.

2. How do you convert km/h to m/s?

To convert km/h to m/s, you need to divide the speed in km/h by 3.6. For example, 250 km/h divided by 3.6 equals 69.44 m/s.

3. How do you convert km/h to mph?

To convert km/h to mph, you need to multiply the speed in km/h by 0.62137. For example, 250 km/h multiplied by 0.62137 equals 155.34 mph.

4. How do you convert meters to kilometers?

To convert meters to kilometers, you need to divide the distance in meters by 1000. For example, 80 meters divided by 1000 equals 0.08 kilometers.

5. How does distance affect G force?

The shorter the distance traveled, the higher the G force will be. This is because G force is directly proportional to the distance traveled. So, in the given scenario, the G force would be higher when traveling from 250 km/h to 80 km/h in 80 meters compared to traveling the same speed change in a longer distance.

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