Quick Answer: The Parallelogram Law Apparatus Gravesand is a force-board apparatus for verifying the parallelogram law of forces and finding the resultant of two concurrent forces using strings, pulleys and weights.
Last updated: October 2026
Key Features
Verifies the parallelogram law of forces
Finds the resultant and equilibrant of concurrent forces
Teaches vector addition by graphical construction
Relates force magnitude, direction and angle in one experiment
About This Product
In a typical experiment, strings passed over pulleys carry weight hangers so that two known forces act at a central point and a third force balances them. Once the ring or knot is in equilibrium, students mark the three force directions on a drawing sheet, draw the vectors to scale and complete the parallelogram. Comparing the diagonal with the balancing force verifies the law.
Frequently Asked Questions
Q1. What is the equilibrant? It is the force that balances the two concurrent forces and keeps the central point in equilibrium. Comparing it with the resultant from the parallelogram verifies the law.
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