Calculating Impulse and Force in a Head-On Collision

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In a head-on collision between a 500kg truck and a 400kg car, both vehicles stick together and move west at 6.00 m/s after the impact. The truck's initial speed is 13.0 m/s, leading to a calculated velocity of 2.75 m/s for the car using the Law of Conservation of Momentum. The discussion highlights the importance of determining the initial direction of both vehicles to accurately calculate impulse and force. Impulse is defined as the change in momentum, and average force during the impact can be found by dividing impulse by the duration of impact, which is 0.6 seconds. The conversation emphasizes that the average force may differ significantly from the peak force experienced during the collision.
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Homework Statement



A 500kg truck collides head on with a 400kg car. They stick together and continue traveling west at 6.00 meters per second. The truck initially travels at 13.0 meters per second. Calculate the impulse and force for the car given that the time of impact was 0.6 seconds.

The Attempt at a Solution



Using the Law of the Conservation of Momentum, I figured out that the car's velocity is 2.75 meters per second and that is as far as I got.
 
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pinksparkles2 said:
A 500kg truck collides head on with a 400kg car. They stick together and continue traveling west at 6.00 meters per second. The truck initially travels at 13.0 meters per second. Calculate the impulse and force for the car given that the time of impact was 0.6 seconds.

Using the Law of the Conservation of Momentum, I figured out that the car's velocity is 2.75 meters per second and that is as far as I got.
There's a piece of information missing. Your answer is correct if the truck was initially heading West. The other possibility is that the car was heading West, very fast, and the truck East.
For each individual vehicle, its change in momentum is the impulse from the other.
The impulse is the integral of force over time, so you can get the average force during the impact by dividing the impulse by the duration. But that could be quite a bit less than the peak force.
 
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The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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