Here are some suggestions for practicing modeling pendulums and bridges:
• Build simple pendulums using strings or threads and different weights like nuts, bolts, marbles, etc. Practice adjusting the length of the string and weight to change the period of oscillation. Time how many seconds it takes for each pendulum to complete 10-20 swings. See how the period changes with different lengths and weights.
• Construct simple harmonic motion pendulums by attaching the hanging weight to a flexible pivot like a wire or string between two supports. This will allow the weight to oscillate in an arc instead of a straight line. Measure and time the oscillation period.
• Make basic beam bridges using boards, cardboard tubes, plastic rods, or wood dowels to support vertical loads. Place different masses in the center of the span and measure how much the bridge deforms. Determine the relationship between load and deflection.
• Build trusses and arches using triangles to provide more support. Experiment with different shapes and arrangements of triangles to maximize load capacity and minimize deflection.
• Create suspension bridges using vertical supports with a hanging cable and transverse beams. Load heavy objects in the middle span and measure how much the bridge sags compared to the unloaded bridge.
• Model the vibration of strings, ropes and springs with different tension, length, thickness and weight attachments. See how the vibration frequency and amplitude changes based on these factors.
• Use motion detectors, vibration sensors or strobe photography to analyze the motion, oscillation and vibration of your models. Make measurements and calculations to determine key principles like frequency, period, acceleration, etc.
• Video record your models in motion and analyze the footage to measure motion parameters through motion tracking software or apps. Measure how motion changes based on the dimension and properties of your model.
Does this give you some good ideas to get started? Let me know if you have any other questions!