Final answer:
Prior to using a ladder, it is essential to inspect for missing rungs to prevent accidents. The integrity of the ladder is paramount for safety, especially when considering the distribution of forces such as gravity and normal force while the ladder is in use.
Step-by-step explanation:
When it comes to checking a portable ladder before use, safety is of utmost importance. A missing rung on a ladder can lead to severe accidents and injuries. Therefore, before ascending a ladder, it is crucial to inspect for any missing rungs, damage, or wear that could compromise its integrity. Additionally, if the ladder is used for performing tasks at heights, such as getting up onto a roof, a thorough check should be carried out to ensure the ladder can support the weight of the user safely, without any risk of collapsing or slipping.
Moreover, considering physics principles, when a ladder is leaned against a wall, the forces acting upon it include the gravitational force and the normal force from the surfaces in contact with the ladder. If a ladder is missing rungs, the distribution of weight and the resulting forces might become uneven, which could potentially lead to an imbalance and cause the ladder to become unstable when in use.