question_answer 65)

                  Why are mountain roads generally made winding upwards rather than going straight up?

Answer:

                  Roads are made winding upwards rather than going straight to make the frictional force large to avoid the skidding of vehicles. Force of friction, when road makes an angle  \[\theta \]  with the horizontal \[=\mu \,mg\,\cos \,\theta \]. 1f \[\theta ={{90}^{o}},\] then force of friction = 0 and there is a great chance of the skidding of vehicles. OR                 If roads are straight, large force is needed by the vehicle to move up.