Some questions about collision

[rendaoer]

I created two cards

Self {
            card: Card::default(),
            rigid_body: RigidBody::Static,
            collider: Collider::cuboid(Card::ASPECT_RATIO, 0.2, 1.0),
            sensor: Sensor,
            transform: Transform::default(),
            global_transform: GlobalTransform::default(),
            visibility: Visibility::default(),
            inherited_visibility: InheritedVisibility::default(),
}

Because the animation and movement are controlled by yourself and are not affected by gravity, RigidBody::Static is used.
And add a Sensor, but if you don't use RigidBody::Static, no collision event will occur
If I use RigidBody::Dynamic it will cause the warning "Dynamic rigid body Entity { index: 10, generation: 1 } has no mass or inertia. This can cause NaN values. Consider adding a MassPropertiesBundle or a Collider with mass."
what should I do?