Finding velocity from g-force?

In summary, the speed of a car before impact in a crash can be determined by calculating the transfer of momentum from the person to the car, taking into account factors such as crumple zones, airbags, seat belts, and flying debris. However, this calculation would be complex and difficult without specific data from similar crash tests. The 20-25g figure mentioned is likely just the peak acceleration and would not provide an accurate estimate of the initial speed.
  • #1
FredGirl13
7
0
Okay so this is more of a theoretical question. If say a car crashed into a stationary truck and the driver experienced around 20-25g, what other factors would you need to find how fast the car was going before impact and how would you do that?
 
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  • #2
A lot, I think the situation you describe is far too complex. Remember that F = dp/dt, and so ultimately it depends on how quickly the momentum the person carries is transferred to the car, and the rock. The car is built to have "crumple zones", there may be airbags involved, the person is strapped into a seat belt, and pieces of the car are probably flying off in random directions.

You'd have to greatly simplify things to do a manageable calculation.
 
  • #3
If you know the acceleration of the person somehow at each time instant you can figure out the initial speed by integration. However I suspect the 20-25g figure you quoted is just the peak acceleration, and you would have no way of estimating the shape of the acceleration curve, which means you can't get a very good estimate. If you could find some accelerometer data from similar crash tests (ie same type of car and same accident type) then you might be able to get some kind of estimate, but without such data you'd just be guessing.
 

1. What is g-force?

G-force, or gravitational force, is a measurement of the force that an object experiences due to gravity. It is typically measured in units of acceleration, with 1 g being equivalent to the force of Earth's gravity.

2. How is velocity related to g-force?

Velocity is directly related to g-force, as g-force is a measurement of acceleration. Any change in velocity, whether it is an increase or decrease, will result in a corresponding change in g-force.

3. How do you calculate velocity from g-force?

To calculate velocity from g-force, you can use the formula v = √(g x r), where v is velocity, g is the acceleration due to gravity, and r is the radius of the circular motion. Alternatively, you can use the formula v = g x t, where t is the time taken to reach the desired velocity.

4. Can you have a negative g-force?

Yes, you can have a negative g-force. This occurs when an object experiences acceleration in the opposite direction of gravity, such as when a car suddenly brakes or when an elevator starts descending.

5. Are there any safety concerns related to g-force?

Yes, there are safety concerns related to g-force, especially for humans. High g-forces can cause discomfort, loss of consciousness, and even injury if sustained for prolonged periods. It is important to properly calculate and manage g-forces in situations such as amusement park rides or space travel.

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