Question

A vehicle is travelling along concave road then along convex road of same radius of curvatures at uniform speed. If the normal reactions on the vehicle as it crosses the lowest point of concave surface, highest point of convex surface are $1.5\times {10}^{4}N,0.3\times {10}^{3}N$ respectively, the mass of vehicle is: $(g=10m/s^2)$

• A. $400kg$
• B. $450kg$
• C. $800kg$
• D. $900kg$

Answer 1

Answer: (D)

$900kg$

Speed is uniform:
At point B: $N_1-mg=\frac{m{v}^2}{R}----\left(1\right)$

At point D: $mg-N_2=\frac{m{v}^2}{R}-----\left(2\right)$
$\left(1\right)-\left(2\right)$
$N_1+N_2=2mg$

$(1.5+.3)\times {10}^4=2mg$

$m=900kg$