Calculating Momentum Change of 70kg Passenger in Car Crash

[cstatepat]

1.A 70 kg front seat passenger is in a car moving initially at 24m/s and is brought to rest by an airbag in 0.4 seconds after a crash.



2. What is the change of momentum of the person in the car



3. mΔv = (70kg)(24m/s) = 1680kg m/s

Am I calculating this right? Is FΔt=mΔv interchangeable depending on the given information?

 

[tiny-tim]

welcome to pf!

hi cstatepat! welcome to pf!

Am I calculating this right?

yes

Is FΔt=mΔv interchangeable depending on the given information?

not following you

∫ F dt is impulse …

if F is constant, that's the same as F∆t​

 

[cstatepat]

hi cstatepat! welcome to pf!


yes


not following you

∫ F dt is impulse …

if F is constant, that's the same as F∆t​

Thank you for the warm welcome!

What I am trying to say is if I am trying to calculate the impulse and I look at my equations FΔt or mΔv based on the information the questions gives me I can use either equation to calculate impulse? For example the question I asked didn't have a given for F so therefore I would try to find the impulse using mΔv.

 

[tiny-tim]

For example the question I asked didn't have a given for F so therefore I would try to find the impulse using mΔv.

oh i see!

yes, exam questions do that …

sometimes they give you the data for one side of an equation, sometimes the other side …

you have to look at what they give you, and work with that!

 

[asteriatic]

Yes, you are calculating the change in momentum correctly. The formula for calculating momentum is p = mv, where p is momentum, m is mass, and v is velocity. In this case, the person's mass is given as 70 kg and their initial velocity is 24 m/s. When the person comes to rest, their final velocity is 0 m/s. Therefore, the change in momentum can be calculated as:

Δp = mΔv = (70 kg)(0 m/s - 24 m/s) = -1680 kg m/s

The negative sign indicates that the momentum has decreased in the opposite direction of the initial velocity.

As for the second question, FΔt = mΔv is a different formula used to calculate the impulse, which is the change in momentum over a period of time. In this scenario, the given information does not include the force or the time, so we cannot use this formula to calculate the change in momentum. However, if we were given the force and the time, we could use this formula to calculate the change in momentum. It is important to use the correct formula based on the given information in order to accurately calculate the change in momentum.