Question

Which of the following are true in case of machine and structure
(A). The members of structure do not move relative to one another.
(B). In a structure energy is transformed into useful work.
(C). The links of a machine may transform both power and motion.
(D). The members of a structure transmit forces only.
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (B), (C) and (D) only.
• C. (A), (C) and (D) only.
• D. (A), (B), (C) and (D).

Hint:

To easily remember the distinction:
- Machine = Motion + Force transmission + Energy modification.
- Structure = Only Force transmission (Static, zero relative motion).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
To solve this, we must understand the fundamental differences between a machine and a structure as defined in theory of machines.

Step 2: Detailed Explanation:
Let us analyze the characteristics of both:

Statement (A): A structure is an assembly of members designed to carry loads and remain in static equilibrium. By definition, there is no relative motion between its constituent members. Thus, Statement (A) istrue.

Statement (B): A machine is a device that transforms available energy (such as chemical, thermal, or electrical energy) into useful mechanical work. A structure, such as a bridge or a truss, does not perform energy transformation or work; it simply supports loads. Thus, Statement (B) isfalse.

Statement (C): A machine consists of kinematically linked bodies. These links are designed to transmit and modify both motion (kinematics) and forces/power (kinetics) to achieve a desired output. Thus, Statement (C) istrue.

Statement (D): Since the members of a structure do not move relative to one another, they do not transmit motion. Their sole function is to transmit forces (tensile, compressive, shear, or bending loads) to the foundation. Thus, Statement (D) istrue.
Therefore, statements (A), (C), and (D) are true, while (B) is false.

Step 3: Final Answer:
The true statements are (A), (C), and (D), which corresponds to Option (C).