I took physics and passed.
Let's look at Newton's second law of motion:
The acceleration of a body is parallel and directly proportional to the net force acting on the body, is in the direction of the net force, and is inversely proportional to the mass m of the body, i.e., F = ma.
In other words...the acceleration of Kenny Bell's helmet was parallel and directly proportional to the net force of Smith's head going to the left just before Bell's shoulder hits him in the chest.
And HuKSer...you're right, the tilt of the helmet is to the right in a " / " direction because Bell hit him in the chin with his helmet - making helmet-to-helmet contact.
Again, this example is simple...face forward, take your right hand and push against your right jaw with your fist...you head turns to te left and tilts to the right...more physics involved here.
Unnecessary roughness. Offense #80. 15 yards from the spot of the foul. First down.