# Calculate direction vector after collision

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So I am trying to figure how to properly identify an objects new direction after colliding with another object. So if I know a bodie's acceleration, velocity, direction it is moving, ect..., how would you go about this? Say a ball is moving towards a wall, I im not sure which direction to apply force at the collision point to that body. I am sure it has something to do with the dot product of the two colliding bodies, but can anyone give some insight?

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For a wall, it's easy. The force direction is always the wall's normal vector (neglecting friction).

For other bodies the force direction depends on the shape and the point of contact.

The velocity of the bodies after collision depends on the masses of the bodies and the restitution, as well as the contact normal. But again, for a perfectly bouncing ball against a wall the solution is easy: reverse the component of velocity along the wall's normal vector.

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The velocity of the bodies after collision depends on the masses of the bodies and the restitution, as well as the contact normal. But again, for a perfectly bouncing ball against a wall the solution is easy: reverse the component of velocity along the wall's normal vector.

Gravity still applies while the wall and ball are in contact. This is irrelevant for rigid collisions but becomes important for other types of collisions (notably, soft-body).

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The velocity of the bodies after collision depends on the masses of the bodies and the restitution, as well as the contact normal. But again, for a perfectly bouncing ball against a wall the solution is easy: reverse the component of velocity along the wall's normal vector.

Gravity still applies while the wall and ball are in contact. This is irrelevant for rigid collisions but becomes important for other types of collisions (notably, soft-body).

Gravity is quite far down the list of effects to consider. Given the nature of the question, I'm sure frictionless rigid bodies is a good starting point.