Depends on how hard you're working, but not many in only 15 minutes. Maybe 150 or so.
However, you do not state if you are running or walking on a treadmill. For information about walking on a treadmill to lose weight, and how to do it correctly, see the page link, further down this page, listed under Related Questions.
Zero. With the exception of sweating, all you're doing in sitting on your rear. This is wrong. If you ever rode a motorcycle you would know how tired you are after a long ride. You are always moving, watching and shifting your weight and your bike. I am not sure of the calories burned but have heard between 25 and 36 calories burned for 15 minutes of riding or 102 calories burned for an hour of riding.
It depends on the speed gone, the kind of bike ridden, and the weight of the person riding. However, on average, approximately 36 calories per mile are burned. Therefore, about 560 calories would be burned.
One of the most accurate bike riding calories burned calculators available online is the one provided by the American Council on Exercise (ACE).
i believe the average for riding 12 mph in an hour is 550 calories but it depends on the person and type of riding
Depends on what you do, and how hard you go at it. For me, it'd be 10-15 minutes of hard bicycle riding. If youi're thinking about weight loss, 150 cals is basically too little to be noticeable.
Yes, it is possible to imagine a bear riding a bicycle.
you will be riding a bicycle
Yes, because you don't inherit the skill of riding a bicycle.
I am not riding
15 miles per hour
not specific enough... could be anywhere from 60-220 bpm
A bicycle