A difficult call to make, and more difficult to explain

[hab_in_exile]

Bob:

Agreed.

I was taking issue with the idea that a ball moving backwards could switch to moving forward without being acted upon by an external unbalanced force. It it started going backwards, it is going backwards.

[PSU213]

Originally posted by hab_in_exile
Earlier someone said that if it goes backwards at 5mph, the net is a forward of 13mph. Nope. If it is going backwards at 5mph, then it is going backwards at 5mph. You are mistaking the application of force with the velocity I think.

I don't want to turn this into a debate over physics, but it appears it is turing out that way. All velocity is relative. When a running player releases a ball it has a velocity relative to the player, relative to the ground, and relative to some fixed point in outer space. Even if the ball is just sitting on the ground it has a velocity relative to that point in space because the earth is racing through the solar system.

If the player is running forward, he may release the ball with a velocity that is backwards in relation to him, but it could be forward in relation to the ground. Assuming no outside forces, at no point does the velocity switch directions (as per Newton's First Law). If it has a forward velocity (relative to the ground) when it leaves his hand, it has a forward velocity when a player catches it.

All that having been said, from an officiating standpoint, I am obviously not going to measure the velocity of the player, the ball, etc. I would have to be even with the player, and clearly see him release it forward to rule it a foward pass.

[LaxRef]

Originally posted by hab_in_exile
If the player releases the ball, backwards, while moving forward at 18mph, it is going backwards and will land (absent a wind) at a location behind where it was thrown. There is no exception to this, as the creation of momentum is impossible (in our universe, if we starting playing football in other universes all bets are off).

Well, sure, if it's actually moving backwards relative to the ground when released, it's going to go backward. But the issue is that he may be throwing it backward relative to his body, but the ball may be moving forward relative to the ground because of his speed.

Try this: drive 65 mph, and just as you pass a parked state trooper, throw a 10 Kg bag of cocaine slightly backward. Now, relative to you, you're throwing it backward, but relative to the state trooper it's still moving about 60 mph and will land at a point past the state trooper. When you get out of jail, please report back with the results!

[hab_in_exile]

Can I experiment by throwing money at a supermodel and then reporting back from the forbidden city instead?

[LaxRef]

Originally posted by hab_in_exile
Can I experiment by throwing money at a supermodel and then reporting back from the forbidden city instead?

Why would you drive past a supermodel at 65 mph?