Settting up force problem with only mass and velocity provided

In summary, a 60kg person in a head-on collision with a car traveling at 15 m/s will decelerate over a distance of 1 m. To find the net force on the person when wearing a seat belt and with air bags deployed, the equation vf^2 = vi^2 + 2aΔx can be used to find the acceleration. This involves finding the final and initial velocities, as well as the change in distance.
  • #1
Zontar
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Homework Statement



A 60kg person is in a head-on collision. The car's speed at impact is 15 m/s. Estimate the net force on the person if they are wearing their seat belt and the air bags deploy. When these two events occur, the passenger decelerates over a distance of 1 m.

Homework Equations



This is a force problem so I reasoned I would need to use F=ma. Below explains other equations I try.

The Attempt at a Solution



This is the way I saw it. I need "F" and I have "m", but they gave me a velocity instead of an acceleration. Although I need an acceleration, I don't know how to set up the kinematics problem (I greatly struggle with this part of each problem) and I try all different things that don't make sense. So I have V_f = 0 m/s while V_i = 15 m/s but all the equations I tried still have an unknown "time" or "distance", which I don't understand how to extrapolate out of the problem. Would I use D_i as 1 m and D_f as 0 m since it decelerates over a distance of 1 m?
 
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  • #2
You are first looking for your acceleration, so you are going to ignore the F=ma until you know "a"

https://www.physicsforums.com/showthread.php?t=110015
find the equation that had distance, acceleration, and a starting velocity, and a final velocity

vf^2=vi^2+2aΔx
 

Related to Settting up force problem with only mass and velocity provided

1. What is the formula for calculating force with only mass and velocity provided?

The formula for calculating force with only mass and velocity provided is F = m x v, where F is force, m is mass, and v is velocity.

2. Can force be calculated if the direction of the velocity is not given?

Yes, force can still be calculated with only mass and velocity provided, even if the direction of the velocity is not given. This is because force is a vector quantity and can be represented by both magnitude and direction.

3. How does increasing velocity affect the force in a force problem?

Increasing velocity will also increase the force in a force problem. This is because force and velocity have a direct relationship, meaning that as one increases, the other will also increase.

4. Is mass a factor in determining the amount of force in a force problem?

Yes, mass is a crucial factor in determining the amount of force in a force problem. The greater the mass, the more force is required to accelerate it at a given velocity.

5. Can force be calculated in a force problem if the mass is given in kilograms and the velocity is given in meters per second?

Yes, force can still be calculated in a force problem if the mass is given in kilograms and the velocity is given in meters per second. This is because both units are part of the metric system and can easily be converted to the appropriate units for the formula (Newtons for force, kilograms for mass, and meters per second for velocity).

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