Question

A plant pruner (cutter) with two studs P and Q are shown on the left in open and closed positions. Which option(s) will allow the pruner to return to its open position?

• A. A
• B. B
• C. C
• D. D

Hint:

For mechanical return mechanisms: \begin{itemize} \item Look for elastic deformation (springs), \item Compression or torsion can both work, \item Rigid components cannot provide restoring force. \end{itemize}

Answer 1

The Correct Option is A, B, C

Step 1: The pruner returns to its open position only if a suitable elastic or torsional restoring element is placed between studs \(P\) and \(Q\). \bigskip Step 2: Such an element must: \begin{itemize} \item Store energy when the pruner is closed, \item Release that energy to push the handles apart, \item Fit mechanically between studs \(P\) and \(Q\). \end{itemize} \bigskip Step 3: Examine each option: \begin{itemize} \item A: A tapered compression spring can be placed between the studs and provide restoring force — valid. \item B: A torsion spring designed to sit around a pivot can exert opening torque — valid. \item C: A standard compression spring can be fitted to push the studs apart — valid. \item Option D: A rigid threaded rod provides no elastic restoring force — invalid. \end{itemize} \bigskip Final Answer: \[ \boxed{\text{A, B, C}} \] \bigskip