Question

Consider the triangle formed by the connecting rod and the crank of an IC engine as the two sides of the triangle. If the maximum area of the triangle occurs when the crank is ${75}^o$, the ratio of connecting rod length to crank radius to

• A. 5
• B. 4
• C. 3..73
• D. 3

Answer 1

The correct option is C 3..73


Area $=\frac{1}{2}\left(AB\right)\left(AO\right)sin{A}^o$

Area will be maximum, when

$\angle A={90}^o$

When $\Delta OAB$ is a right-angled triangle.

$\frac{l}{r}=tan{75}^o=\frac{AB}{OA}=3.73$

$\frac{l}{r}=3.73$