# Physics

• I might miss something obvious, or not.

Question 1
I have 2 objects set as “physics” located at same height.
The scene or world has the gravity set @-9.8m/s2 on Y axis.
Object 1 has all parameters set to 0 except Mass = 100
Object 2 has all parameters set to 0 except Mass = 0.1
So, why are they falling at same speed? They should not...

Question 2
My objects are “balls” falling on a “wall” object at the base of screen. If I set “bounce” to them and 0 bounce to wall object they will not react at collision with “wall”, will just stop on top of it with no other reaction. If I set “bounce” to the “wall” object then the “balls” will bounce back when collision is detected.
What is or I am doing wrong?

Thanks!

• Question 1: This is a just a little misunderstanding of physics. :) People think larger masses fall at a faster speed, but in reality, that's not the case -- this can be observed in real life: a rock and a heavy weight both accelerates around 10m/s per second on Earth! If you want something to fall at a different speed, you can apply a different force of gravity on the object or modify its air resistance.

Question 2: This can be hard to explain, so I'll try my best! An object with 0% bounce would absorb all kinetic energy from an object regardless of how bouncy the other object is. An object with 100% bounce would use all kinetic energy to push back another object. For something to bounce, both objects must be bouncy. When an object collides with another object, it considers both objects' bounciness -- I'm assuming the bounciness % are multiplied which is used to determine how much an object is "pushed back."

Please let me know if you think something is wrong with my explanation. I'd like to help and be supportive! :)

• Thanks for the explainer @RobinsonX
1 - so the physics engine assume “free fall” where only G force is taken in consideration. I guess this is the right way for the engine.

2 - while the answer given is clear, I’m not sure the physics on Earth works in that way. I will do my research on this.

Thanks for helping!

• No problem! Maybe the second one wouldn't translate into real life, but it definitely applies in hyperPad.