[填空题]
A roller coaster car wih2l fcwo4 w (3x2k03mexr+tn jth a mass of 80 kg moves on the di3 )c3 ocxqv c8n:3e8 tt6softrack shown in the diagram startinx3c8edoc36iso t:f nv cqt38)g from point A.
At points B and C, the track approximates a circular path so that the radii at at B and C are $12,m$ and $18\,m$ respectively.
1.Compare the normal force exerted by the track on the car at point B is the corresponding force at point C.
2.Draw and label the free body diagram of the car at point C.
3.Calculate the maximum speed of the car at point C so that it could remain on the track. $v_{max}$ = $ms^{-1}$
