Skip Navigation
Search
- Sections
- A. General Materials & Mathematics
- B. Statics
- C. Kinematics & Dynamics
- D. Rotational Mechanics
- E. Gravitation & Astronomy
- F. Fluid Mechanics
- G. Vibrations & Mechanical Waves
- H. Sound
- I. Thermodynamics
- J. Electrostatics & Magnetostatics
- K. Electromagnetic Principles
- L. Geometrical Optics
- M. Wave Optics
- N. Spectra & Color
- O. Vision
- P. Modern Physics
Equilibrium Paradox - Scales And Pulley
Purpose
Counterintuitive demonstration involving pulley system.
Equipment
Two spring scales and pulley, assembled as photographed.
Suggestions
Let your students vote before performing the experiment.
Images
Description
A frame containing the pulley and the lower scale hangs from the upper scale as photographed. The initial weight of the lower scale, pulley, and frame together is about 5 Newtons, as read on the upper scale; initially the lower scale reads zero. When you pull gently on the free end of the rope until the lower scale reads 10 Newtons, what will the upper scale read: 5N, 10N, or 15 N?
References
PIRA 1M20.15) See Demonstration Reference File for original sources of this demonstration.
-
See pagesb1. center of mass statics
-
See pagesb2. equilibrium of forces & torques
-
See pagesb3. simple machines
-
See pagesb4. elasticity
-
See pagesb1. center of mass statics
-
See pagesb2. equilibrium of forces & torques
-
See pagesb3. simple machines
-
See pagesb4. elasticity
Physics Lab Demos