Can anyone who has a better knowledge of physics (that shouldn't be difficult to find) help me out here with the following.
Lets say I free wheeled down a fairly steep hill and recorded the max speed I achieved during the descent. Lets say I then placed several lead weights into pockets in my clothing, which now meant I was now say 10kg heavier but with no added wind resistance. Would I now achieve a higher max speed during the descent assuming I had pushed off on the bike with equal force as the first descent.
I think intuitively on the second ride I will reach a higher max speed, if this is correct then does that mean with electrical assist bikes the lighter they are might mean you could actually end up being slower than a heavier bike when it comes to hills.
This is how I think this might be the case. Assume we have a big up and then down hill section and two racing bikes, one say 4 kg lighter than the other. On the way up each bike is ridden on max assist level and we go up at 15.5 mph assume we are not fit enough to ride up the hill un assisted.
On the way down the heavier bike will reach a higher max speed than the lighter one is my thinking correct here?
on the way down, the heavier bike + biker will have transformed more potential energy into kinetic energy. If it is the same biker and in same atmospheric condition, the heavier bike will win on the downhill leg.
On the uphill leg, the heavier bike needs more energy to climb, so the lighter bike will win.
to work out the difference when both legs are added together, if there is no air resistance, then there is no winner.
That's what SW said.
Air resistance turns kinetic energy into wasted heat. Air resistance increases to speed to power 3 (speed * speed * speed), a lot more heat is wasted on the downhill leg than on the uphill leg.
It follows that the winner of the downhill leg is the heavier bike, will have wasted more energy into heat overall, he'll be the loser of the overall race.
