Need help finding change in velocity and momentum

In summary, the two automobiles, one with a mass of 1500 kg traveling at 24 m/s and the other similar and parked, collide and remain joined together for a duration of 0.020s. The pavement has a coefficient of friction of 0.63. The friction force produced is 18541 N, resulting in a change in momentum of 371 kg*m/s and a change in speed of 0.15 m/s. The error in the equation is using the incorrect mass of the offending vehicle, which should be 1500 kg instead of the originally used 3000 kg. After this correction, the equation is accurate.
  • #1
Sneakatone
318
0
An automobile of mass 1500 kg traveling at 24 m/s crashes into a similar parked automobile. The two automobiles remain joined together after the collision. Suppose that the collision last for 0.020s, and pavement with a coefficient of friction uk=0.63. What change of momentum and what change of speed does the friction force produce in the joined automobiles in the interval of 0.020 s ?

Delta p=?
Delta v=?

for p I did 24m/s *1500kg=36000
3600/12m/s=3000
The Friction force = µ . m . g =0.63*9.81*3000=18541 N
The change in momentum produced by this force = F . t =18541*0.02=371 kg*m/s
delta p=36000-371=35629 kg*m/s

to get v
35629/3000=11.87m/s
12m/s-11.87m/s=0.15 m/s
 
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  • #2
What exactly do you need help with?
 
  • #3
the numbers that I input are apparently wrong.
 
  • #4
I am not sure what you mean by this. I have checked your computations and my results agree with yours.
 
  • #5
Sneakatone said:
The Friction force = µ . m . g =0.63*9.81*3000=18541 N
Does the offending vehicle have its brakes on?
 
  • #6
it does not
 
  • #7
Sneakatone said:
it does not

So... what's the error in the equation I quoted?
 
  • #8
I should have used 1500kg for mass instead.
 
  • #9
Sneakatone said:
I should have used 1500kg for mass instead.
Exactly. Does it accept your answer now?
 

1. How do I calculate change in velocity?

To calculate change in velocity, you need to subtract the initial velocity from the final velocity. This will give you the magnitude and direction of the change in velocity.

2. What is the equation for momentum?

The equation for momentum is P = mv, where P is momentum, m is mass, and v is velocity. It is measured in kg*m/s.

3. How do I find the final velocity given the change in momentum?

To find the final velocity, you can use the equation vf = vi + (ΔP/m), where vf is the final velocity, vi is the initial velocity, ΔP is the change in momentum, and m is the mass of the object.

4. Can you provide an example of calculating change in velocity and momentum?

Sure, let's say an object with a mass of 2 kg has an initial velocity of 10 m/s and a final velocity of 15 m/s. The change in velocity would be 15 m/s - 10 m/s = 5 m/s. To calculate the change in momentum, we can use the equation ΔP = mvf - mvi. Plugging in the values, we get ΔP = (2 kg)(15 m/s) - (2 kg)(10 m/s) = 10 kg*m/s.

5. What factors can affect the change in velocity and momentum?

The change in velocity and momentum can be affected by factors such as the mass of the object, the initial and final velocities, and external forces acting on the object (such as friction or gravity). Additionally, the conservation of momentum principle states that the total momentum of a closed system remains constant, so any changes in velocity and momentum of one object will affect the other objects in the system.

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