EXAMPLE EXERCISE 1

Apuntes

EXAMPLE EXERCISE 1 A pair of scissors is used to cut an object that puts up a resistance of 20 N. The distance from the fulcrum to the point of resistance is 10 cm, and the force is applied 5 cm from the fulcrum. What force is required to cut the object? What class are the levers of the scissors? **Data:** R = 20 N **Unknown:** E = ? **A₁ =** 10 cm **A₂ =** 5 cm **Solution:** Applying the law of the lever: E · A₂ = R · A₁ Rearranged: E = R · A₁ / A₂ Substituting the values: E = 20 N · 10 cm / 5 cm = 40 N We can confirm that the required force is greater than the resistance. This is why pruning shears, staplers, and pliers (all objects that need to overcome a strong force) have short blades (A₂) and long handles (A₁). This is not necessary for scissors used to cut paper or fabric: it is better for these to have long blades so they can cut more with each action. **Levers of the scissors:** They are two class 1 levers joined at the midpoint. The fulcrum lies between the effort and the resistance. --- **EXAMPLE EXERCISE 2** A nutcracker cracks a walnut with a force of 3 N. The nutcracker measures 15 cm, and the walnut is located 6 cm from the ful...