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    The point is transfer of momentum.. Archived Message

    Posted by Shyaku on March 27, 2021, 7:40 pm, in reply to "Inertia.."

    Yeah, so the stationary object has no momentum, but momentum can be transferred to it:

    m1v1 = m2v2

    - Remember that one?

    Yes, obviously the stationary experiences friction in this case (unlike Newton’s cradle, which is in air).

    So you need to impart a force large enough to overcome frictional force of the sand on the ship.

    In other words, since work = force x distance, and since you can estimate both frictional force and distance you want to move the ‘stuck’ ship (say 5 meters), you can therefore estimate the energy (work) required.

    That energy is the kinetic energy of the moving ship, half-MV-squared. Where M and V are mass and velocity of the moving ship.

    - Remember that one?

    In this case, you prefer to have a moving ship with high mass but low velocity to prevent penetration of the stationary ship (low mass but high velocity being a bullet or a cosmic subatomic particle).

    So yeah, an equally massive object can dislodge it if force is transmitted at the center of gravity of both.

    - Got it? :-)

    - Shyaku

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