Final answer:
Using a paint-can opener as a lever results in the output force being greater than the input force. The opener acts as a class 1 lever and not as a wheel and axle, your hand applies the input force and does not serve as the fulcrum, and the direction of the output force is opposite to that of the input force.
Step-by-step explanation:
When using a paint-can opener as a lever to pry off a lid, it helps to apply concepts of simple machines and levers. We know that levers can multiply forces depending on the position of the fulcrum and lengths of the lever arms. The paint-can opener is a class 1 lever, where the fulcrum is at one end (in this case, the rim of the paint can), the input force is applied at the other end (by your hand), and the output force acts in between (on the lid). Looking at the provided options and based on knowledge of levers:
- The output force is indeed greater than the input force because levers can act to increase the force that is applied, much like the scenario with a nail puller.
- Your hand does not act as the fulcrum; it applies the input force. The fulcrum is the point on which the lever pivots, which in this case, is the rim where the opener makes contact.
- The paint-can opener does not act as a wheel and axle; it functions as a lever.
- The output force is not in the same direction as the input force. The input force is applied downwards by your hand, while the opener lifts the lid upwards, making the direction of the output force opposite to the input force.
Based on this analysis, the correct answer would be Option 1: The output force is greater than the input force.