# Rigid Body and Material / Table Collider and Trigger

Hello, I just wanted to confirm.
Since my English not too good so I need some help.

Kinematic: the bouncing will direct some position we target
Dynamic: Normal Physics
Static: no Physics implement
Is this right?

On the table, we saw Collider and trigger event.
If object a has a trigger and object b no trigger then the event still triggered and no collision happen.
Is this right?

I found we can put material in a rigid body, why put it in a collision?

Hi Benny,

#1: You are right.
#2: If the game object has no collider attached, no collision event can be triggered by this game object.
#3: The Rigidbody on a parent game object acts as a compound collider. It collects the collision information from the colliders on the child game objects. If you attach a material to the rigidbody, the colliders on the children get this material attached unless they have their own material.

Did this clear it up for you?

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clarify about this one if i put the material on rigid body, so the child will be have material too?
but if put on colider the chlid game object wont have the material?

btw i kinda forget something.
when i move paddle or ball the position of x n y is 16:12 (4:3)

I understand when on bg i use 1440x1080 and 90 pixel/unit.
but why on ball or paddle the pos x n y still 16:12

The Colliders on the child get the material from the Rigidbody unless the Collider on the child already has got a material assigned.

I understand when on bg i use 1440x1080 and 90 pixel/unit.
but why on ball or paddle the pos x n y still 16:12

Youâ€™ll have to do the maths to figure out whatâ€™s going on here. Rick calculated his values for a 4:3 aspect ratio and a resolution of 800 x 600 respectively. Your values have to be the same as his to get the same result as he without changing anything.

What kind math solution i need use?

resolution i use is 1440x1080.
but in BG i use 90 ppi(pixel per unit.)
i understand my transform is end up 16:12.

but my paddle ppi is 120, the maksimal pos X on this case is 16.
didnt it should be 12:9?