Allied & ICAR Exam Bank • ALLIED_2813NAT • 2 Marks
Section 2: Farm Machinery
Machine Design
Subtopic: Measurement of force, stress, torque, speed, displacement and acceleration on machine elements – shafts, couplings, keys, bearings and knuckle joints
Question Statement:
A rectangular sunken key has width $w = 12\text{ mm}$, height $h = 8\text{ mm}$, and length $L = 50\text{ mm}$. If the shear stress in the key is $\tau = 40\text{ MPa}$, the shear force transmitted by the key ($F = \tau w L$) in kilonewtons is:
Answer Key:
24
Step-by-Step Solution & Explanation
Shear area $A_s = w L = 12 \times 50 = 600\text{ mm}^2$. Force $F = 40\text{ N/mm}^2 \times 600\text{ mm}^2 = 24000\text{ N} = 24\text{ kN}$.