$12$mm diameter bars are used as longitudinal bars of a concrete pavement. It is spaced at $600$ mm on center. The width of the roadway in meters is $9$ m and the coefficient of friction of the slab on the subgrade is $2.$ The thickness of the slab is $150$ mm$.$ If the allowable bond stress is $0\mathrm{.}83$ MPa, determine the length of the longitudinal bars.

A$\mathrm{.}601$ mm

B$.610$ mm

C$.2120$ mm

D$.1220$ mm

The middle ordinate of a simple curve is $33\mathrm{.}49$ m while the length of its long chord is $250.$ What is the lenght of its radius

A$.175$ m

B$.250$ m

C$.225$ m

D$.275$ m

A car weighing $800$ kg runs at $60$ kph around an unbanked circular curve with a radius of $100$ m$.$ Determine the coefficient of friction between the tires and road to prevent the car from sliding.

A$.0$

B$.0\mathrm{.}136$

C$.0\mathrm{.}427$

D$.0\mathrm{.}283$