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Mass & Gravity

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  • 23-09-2019 8:07pm
    #1
    Poulgorm
    Registered Users Posts: 776 ✭✭✭


    2 cars, travelling horizontally, crash into each other, on earth.

    Identical cars travelling with the same velocity, crash into each other on the moon. Do they inflict identical damage on each other in both scenarios?

    Same mass, but weigh about 1/6 on the moon. Same momentum (mv) and energy (1/2 mv squared), so damage should be the same(?). If this is the case, I can't get my head around it.

    Anybody take me out of my misery?


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    #2
    Bit cynical
    Registered Users Posts: 2,338 ✭✭✭Bit cynical


    The key concept is mass which does not depend on gravity. Two high mass objects will break apart if unless built strongly if they crash into each other. The higher the mass the greater the energy that will be dissipated when the crash occurs at a given velocity.

    The weight of an object on the other hand depends on both the mass and the strength of the gravitation field. Since the gravitational field is fairly constant everywhere on Earth, we tend to identify mass with weight but they are different concepts.

    So the damage will be much the same on Earth as on the Moon. The main difference is that the bits will be thrown farther and higher on the Moon due to its lower gravity and lack of air resistance.


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