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Throwing Knife

  1. Nov 26, 2013 #1
    When a throwing knife is thrown why does it only hit its blade end ( not the grip end)? The knife has been imparted with a spin and there is a 50:50 probability that its blade end will hit (actually a bit less).
    It would be better if you explain assuming the blade's CM has velocity 'v' and is imparted with an angular velocity ω and its target is at distance 'd' if the explanation is complicated.
    I think it is because the knife only spins once and the brain automatically calculates the angular velocity which needs to be imparted.
  2. jcsd
  3. Nov 26, 2013 #2


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    My understanding is that this happens primarily because the center of mass of the knife is towards the point end. As it moves right up close to the target, either the last rotation causes it to stick (by the point), OR it causes the handle to not hit the target and there is then another revolution that embeds the point.

    EDIT: and by the way, they DON'T always stick by the point. Bad timing can occur and they bounce off, so part of the explanation is the skill of the thrower.
  4. Nov 26, 2013 #3
    Wikipedia- http://en.wikipedia.org/wiki/Knife_throwing#Basic_principles
    Knife throwing, whether in a martial or sport application, involves the same basic principles of mechanics. The objective in each case is for the point to stick into the target with a sufficient amount of force. For this to be successful, accuracy, distance, number of rotations and placement of the body all must be taken into account unless a no-spin technique is employed by the thrower (there are spin and no-spin throwing techniques). If the thrower uses a spin technique, the knife will rotate during flight.[1] This means that the thrower, assuming he is throwing the same way every time, must either choose a specific distance for each type of throw or, more practically, make slight adjustments to placement of the knife in the hand as well as angle of release and rotation of the wrist. Variations in throw technique can allow great accuracy and range. Throwers may also need to adjust for throwing off-center, around corners, and while running.
  5. Nov 26, 2013 #4
    I used to play with throwing knives a lot last summer and the blade doesn't always hit your target. I've gotten the handle stuck in a tree before. You have to learn how to throw them. There is a certain distance:rotation ratio you have to follow
  6. Nov 26, 2013 #5
    Last edited by a moderator: Sep 25, 2014
  7. Nov 26, 2013 #6


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    Around corners? Cool!
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