Question

When a crane is moving a load, it operates within a ___: if a worker is within that area, he or she could be caught-in-between the crane or its load and either the ground or another piece of equipment.

a) Safe zone
b) Restricted area
c) Danger zone
d) No-entry zone

Answer 1

The total work done by the crane on the construction materials is calculated by considering the work done in each phase of force application: an initial and final phase of increasing and decreasing force respectively, and a middle phase of constant force. The total work sums up to 500 kJ.

Step-by-step explanation:

Crane Lifting Construction Materials

When calculating the total work done by a crane lifting construction materials, it is essential to consider the different phases of force exertion and the corresponding distances. Over the first 10 m, the force increases linearly from 0 kN to 10 kN. Therefore, the work done in this phase is the area under the force-distance graph, which is a triangle. The formula for the area of a triangle is ½ × base × height, which equates to ½ × 10 m × 10 kN = 50 kJ (since 1 kN × 1 m = 1 kJ).

For the next 40 m, the crane exerts a constant force of 10 kN. The work done here is simply the force times the distance. Hence, 10 kN × 40 m = 400 kJ.

In the final phase, as the force decreases back to 0 kN over another 10 m, the work done is another triangular area similar to the first phase, which is another 50 kJ.

Adding these amounts together, the total work done on the construction materials during the entire lift is 50 kJ + 400 kJ + 50 kJ = 500 kJ.