Why mountain roads are winded up rather than keeping them straight? [closed]

In my opinion, to prevent the line passing from the center of gravity of a body (e.g bike or car) trying to climb the mountain or hill to fall outside the base of support so to maintain stable equilibrium and balance. This prevents them from falling down the hill. Is my answer right?

closed as unclear what you're asking by ACuriousMind♦, John Rennie, Kyle Kanos, Brandon Enright, BMSJul 28 '14 at 15:56

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• I really don't get what you are trying to ask here? – Bernhard May 5 '14 at 16:08
• Hint: the inclined plane is one of the 6 fundamental machines. – The Photon May 5 '14 at 16:09
• I too am a little confused here. What do you mean by "straight"? – Kyle Kanos May 5 '14 at 16:37

• Depending on the region, to climb a mountain following a straight line often means climbing at angles greater than $\pi/4$, which is very steep for most cars. Descending such steep road that is also long means that you risk brake failure, in other words you risk your life. – auxsvr May 5 '14 at 19:19
To reduce risk of slipping by increasing friction between tyres and road. while going up a mountain the opposing frictional force $F = μN =mg\cos\theta$ where $\theta$ is the angle of slope with horizontal .To avoid skidding $F$ should be large,so $\cos\theta$ should be large and hence $\theta$ should be small.so roads are made winding upwards.the road straight up would have larger slope.