1G10.60 • Spring Scale on Pulleys
Location: Cabinet 4
Both masses are 200 g.
Photo shows the demonstration used at the University of Texas at Austin
Both masses are 200 g.
Photo shows the demonstration used at the University of Texas at Austin
Concepts Conveyed:
- A spring scale measures force in a balanced system.
- In the string-spring configuration on the pulleys, the scale measures tension. Since the system is still balanced, the tension would be equal to the gravitational force on the object.
Instructions / Notes:
- Hold the scale by the top and have the mass hang on the hook. Then read what force is applied to the scale (~ 2 N).
- Show the students that the scale reads that a mass of 200 g applies a force of about 2 N on the scale holding it. Then ask what they expect the scale to read in the pulley configuration if equal masses are applied to both sides of the scale.
- Then change the configuration to the pulley system by hanging both masses on the pulleys on opposite sides. Read the force applied (~ 2 N)
- Both measurements should be around the same value (The scale is not very precise and can read a small range of numbers that aren’t exact).
Demo Staff:
- Assemble the stand with the pulleys clamped on the very far edges of either side of the rod and have them face vertically upward (for more height)
- Ensure the masses are attached to their strings and their strings secured to either side of the scale.
Last updated on April 22, 2025