Experiment: Crane

Using a line to extend a beam from a post is an equilibrium problem with a number of examples in real life such as a hanging bridge, construction cranes, hanging neon signs.

Setup the experiment as in the figure with a 200g hanging mass. Change the string length and position the clamp on the upright pipe such that the ruler (beam) is level. You should have a unique setup from your partner.

• Sketch the setup into your notes and measure/record all angles. Read the scale with the 200g mass. Also measure the mass of a sample wooden meter stick.
• Draw a free body diagram and include all your measurements. Note, the meter stick mass adds into the vertical forces by distributing it mass equally between the two end points.
• Determine the tension in the meter stick from the measured angles and the measured tension in the string
• Determine the vertical component of the tension in the string. Compare the magnitudes of this force component to the force due to the hanging mass and the meter stick by writing a statement using percent difference.
• Repeat the experiment with a 300g mass (ensure the beam/ruler is horizontal).  Just take the measurements for this and leave the calculations for a future time.

Notice the similarity of this experiment to cranes used in construction.