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Figure 7 shows two of the forces acting on a uniform ladder resting against a vertical wall - AQA - A-Level Physics - Question 5 - 2017 - Paper 1
Question 5
Figure 7 shows two of the forces acting on a uniform ladder resting against a vertical wall. The ladder is at an angle of 60° to the ground. *Explain how Figure 7 s... show full transcript
Worked Solution & Example Answer:Figure 7 shows two of the forces acting on a uniform ladder resting against a vertical wall - AQA - A-Level Physics - Question 5 - 2017 - Paper 1
Step 1
Explain how Figure 7 shows that the friction between the ladder and the wall is negligible.
Answer
Figure 7 illustrates that the force from the wall acts horizontally, perpendicular to the ladder, indicating no component of the force is acting along the wall. This implies that there is no need for friction to prevent slipping, as the forces are balanced.
Step 2
Draw an arrow on Figure 7 to show the direction of the resultant force from the ground acting on the ladder. Label your arrow G.
Answer
An arrow pointing upwards from the point of contact between the ladder and the ground should be drawn, indicating the direction of the resultant force from the ground acting on the ladder. The arrow should be labeled 'G'.
Step 3
Calculate the magnitude of the resultant force from the wall on the ladder.
Answer
To calculate the resultant force, we can use the principle of moments. The weight of the ladder is 390 N, acting at its center, which is 4 m from either end. The vertical component can be calculated as follows:
Using the sine component, we have:
Thus, the resultant force from the wall can be calculated as:
Step 4
Suggest the changes to the forces acting on the ladder that occur when someone climbs the ladder.
Answer
When someone climbs the ladder, the following changes occur:
- The vertical reaction force from the ground increases due to the added weight.
- The direction of the resultant force from the ground changes, as the center of mass of the ladder shifts upwards.
- The force exerted by the wall may decrease slightly due to the increased load causing the ladder to exert more force into the wall, resulting in a greater likelihood of slipping.