A car moves along a curved road of diameter 2 km. If the maximum velocity for safe driving on this path is 30 m/s, at what angle has the road been banked? (Ignore friction.)
A) 11°
B) 22.6°
C) 45.2°
D) 5.26°

Respuesta :

leena

Hi there!

Ignoring friction, we know that the centripetal force experienced by the car is due to the normal force exerted by the road.

We can do a summation of forces in both the horizontal and vertical directions.


Vertical:
[tex]W = Mg[/tex], force due to gravity

[tex]Ncos\theta[/tex], VERTICAL component of the normal force.

[tex]\Sigma F_y = Ncos\theta - Mg\\\\Mg = Ncos\theta[/tex]

Horizontal:
[tex]Nsin\theta = F_{Hnet}[/tex]

The net horizontal force is equivalent to the centripetal force:
[tex]Nsin\theta = \frac{mv^2}{r}[/tex]

We can solve for theta by dividing:

[tex]\frac{Nsin\theta = \frac{mv^2}{r}}{Ncos\theta = mg}[/tex]

Simplify:

[tex]tan\theta = \frac{ \frac{v^2}{r}}{ g}\\\\tan\theta =\frac{v^2}{rg}[/tex]

Solve:

[tex]\theta = tan^{-1}(\frac{v^2}{rg}) = tan^{-1}(\frac{30^2}{(1000)(9.8)}) = \boxed{5.26^o}[/tex]