Question by newuser1992 · Jul 15, 2016 at 03:20 AM · rigidbody fixedupdate friction forces collission

How do I get force applied on an object by unity physics?

Suppose I add a force of 10N to a rigidbody (rigidbody.AddForce) and due to external forces such as collisions, friction, air drag etc the net force applied on the body is now reduced. Is there a way to get the force applied by these 'other' factors.? When does unity calculate all these forces. Suppose I add the force in fixedUpdate is there any way for me to calculate these 'other' forces using velocities obtained from two consecutive fixedUpdate calls?

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_Yash_ · Jul 15, 2016 at 05:17 AM 0

I did an experiment on this, when you add force or torque it will be converted to velocity and angular Velocity in the NEXT fixed update cycle. So all the other forces will start affecting from next fixed update call.
I added (10,0,0) force to sphere and debuged the velocity before and after that, and Drag was 0.5 and results were obvious.

frame num | velocity.x
0 | 0 (force was added in this cycle)
1 | 5 (force * drag)
2 | 0.25
and so on...

to debug physics you can change Time.fixedDeltaTime to higher value 1 and use Editor Steps. Hope this helps.