A training rig models a tower crane. A horizontal boom turns about a pivot at the mast. The weight of the boom is negligible, and all the forces in the table act vertically.
The boom is initially balanced.
| Force | Side of pivot | Force in N | Distance from pivot in m |
|---|---|---|---|
| load | right | unknown | 1.20 |
| counterweight A | left | 180 | 0.50 |
| counterweight B | left | 120 | 0.30 |
Calculate the weight of the load.
The load is moved to a distance of 1.50 m to the right of the pivot and counterweight B is removed.
Explain why the boom begins to turn clockwise.
A technician applies an additional downward force at a distance of 0.75 m to the left of the pivot.
Calculate the additional force needed to hold the boom horizontal.