Which of the following is a coarse crusher used in mechanical operations?

• (A) Ball Mill
• (B) Jaw Crusher
• (C) Hammer Mill
• (D) Fluid Energy Mill

Forces whose line of action passes through a common point are known as what?

• (A) Parallel Forces
• (B) Coplanar Forces
• (C) Concurrent Forces
• (D) Collinear Forces

For a DC power source for arc welding with characteristics \(3V + I = 240\), what voltage \(V\) yields maximum power?

• (A) \(20 \, V\)
• (B) \(30 \, V\)
• (C) \(40 \, V\)
• (D) \(60 \, V\)

The polar section modulus for a circular shaft of diameter \(d\) is given by which formula?

• (A) \( \dfrac{\pi d^3}{16} \)
• (B) \( \dfrac{\pi d^3}{32} \)
• (C) \( \dfrac{\pi d^4}{32} \)
• (D) \( \dfrac{\pi d^4}{16} \)

What is the natural frequency of a free vibration system defined by the equation \( \ddot{X} + 36\pi^2 X = 0 \)?

• (A) \(3 \, Hz\)
• (B) \(6 \, Hz\)
• (C) \(12 \, Hz\)
• (D) \(18 \, Hz\)

Which translatory joint in a robot configuration is known as a sliding joint?

• (A) Revolute Joint
• (B) Prismatic Joint
• (C) Cylindrical Joint
• (D) Spherical Joint

A ball is thrown vertically upward with a velocity of \(5 \, m/s\); if it takes 10 sec for the upward journey, how long does the downward journey take?

• (A) \(5 \, s\)
• (B) \(10 \, s\)
• (C) \(15 \, s\)
• (D) \(20 \, s\)

What is the stress developed when a steel rod of radius \(10 \, mm\) is stretched by a \(100 \, kN\) force?

• (A) \(159 \, MPa\)
• (B) \(318 \, MPa\)
• (C) \(100 \, MPa\)
• (D) \(200 \, MPa\)

Which mechanical drive is specifically used to impart a reciprocating or oscillatory motion to another body in contact?

• (A) Gear Drive
• (B) Belt Drive
• (C) Cam and Follower
• (D) Chain Drive

When a ball mill rotates at a speed higher than the critical speed, what happens to its efficiency?

• (A) It increases continuously
• (B) It remains constant
• (C) It decreases
• (D) It becomes maximum