Question:easy
The virtual work principle states that ______.
The virtual work principle states that ______.
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Think about what equality virtual work sets up between outside loads and internal deformation.
Updated On: Jul 28, 2026
- external virtual work is equal to internal virtual work
- there is equilibrium of external and internal forces
- virtual work is inversely proportional to virtual displacement
- the potential energy of the system is equal to its kinetic energy
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: State what a virtual displacement is.
A virtual displacement is a small, imaginary displacement consistent with the supports, applied to a body already in equilibrium.
Step 2: Write the virtual work statement.
For the body to stay in equilibrium under this imaginary displacement, the work done by the external loads must equal the work done by the internal forces as the structure deforms: $W_{external} = W_{internal}$.
Step 3: Rule out the other statements.
Force equilibrium alone does not define virtual work, there is no inverse proportionality in its definition, and potential energy equalling kinetic energy belongs to dynamics, not this principle.
Final Answer:
The principle links external and internal virtual work directly. \[ W_{ext} = W_{int} \]
A virtual displacement is a small, imaginary displacement consistent with the supports, applied to a body already in equilibrium.
Step 2: Write the virtual work statement.
For the body to stay in equilibrium under this imaginary displacement, the work done by the external loads must equal the work done by the internal forces as the structure deforms: $W_{external} = W_{internal}$.
Step 3: Rule out the other statements.
Force equilibrium alone does not define virtual work, there is no inverse proportionality in its definition, and potential energy equalling kinetic energy belongs to dynamics, not this principle.
Final Answer:
The principle links external and internal virtual work directly. \[ W_{ext} = W_{int} \]
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