The general formula is: Momentum = (mass) x (speed)
I never like to just write a bunch of algebra without explaining it.
But in this particular case, there's really not much to say, and
I think the algebra will pretty well explain itself. I hope so:
Original momentum = (original mass) x (original speed)
New momentum = (2 x original mass) x (2 x original speed)
= (2) x (original mass) x (2) x (original speed)
= (2) x (2) x (original mass) x (original speed)
= (4) x (original mass) x (original speed)
= (4) x (original momentum).
You sure wouldn't want something like cm/s or (yikes cm/hr). You want a reasonable number for sports usually between 0 and 100
Km / hour would be a good choice.
The next town to where I live is 25 km away. On a good day, I can make it there in about 3/4 of an hour.
Speed = 25 km / 0.75 hour = 33.3 km/hour. That's actually a little fast most of the time. But you should understand what I mean.
The local charging of the comb is due to induction. The negative object's charge pushes electrons in the comb away from the side close to the charged object causing that part to be positively charged. Note that the comb's net charge is still zero provided it doesn't touch the object. When you move the comb away its electrons will redistribute.
