Slow it down to where once you're at the start of the curve you're going no more than 35. That's how I personally feel safest, anyway. Once you're going straight, or out of the curve, unless otherwise posted I believe it's safe to resume the 45mph speed limit
The 35 mph is an advisory speed limit for ideal conditions and also factoring in how easily a driver can make that turn at that speed. So while you won't get a ticket for going 40 around the curve, it is safer to go 35 or less depending on conditions. The speed that is posted is based on an engineering study of the location, so it's not just arbitrary. http://mutcd.fhwa.dot.gov/htm/2009/part2/part2c.htm#section2C08
If you're asking for your driving test, the answer is slow down as you approach, so that you enter the curve at 35 mph.
8 months ago
Last edited at 12:02PM on 7/16/2013
Newton's first law of motion says that a body in motion tends to stay in motion. When you are driving a car on a straight road, if you simply take your foot off the gas, you will start to slow down, but you will continue in the same direction. If the road then starts to direct you to the left or right, you will continue straight unless you change the direction of your car from straight ahead to that of the curve.
Your ability to change your direction is a function of your speed, the coefficient of friction between the road and your tires, and the design (banking or tilt) of the road to oppose the centrifugal motion your car generates when you change direction.
The speed limit gives you an idea of a safe speed at which you can navigate the curve without going off the road. I suspect you won't go off the road at at 45 mph, but you probably would at 80.
So use your breaks to slow down somewhat, but don't lock your wheels.