Atwood's machine, showing energy bar graphs

Show energy for:
Mass of block 1 (on the left)
0.1 kg 2.0 kg
Mass of block 2 (on the right)
0.0 kg 2.0 kg
Mass of the pulley
0.0 kg 2.0 kg
The pulley is a

The simulation shows the flow of energy for an Atwood's machine, which is simply two blocks connected by a string passing over a pulley. Block 1 is the blue block on the left, and block 2 is the red block on the right. You can view the energy from seven different perspectives, ranging from defining the system to be the Earth and the two blocks and the pulley, to just one of the blocks or just the pulley.

Note that the simulation uses 10.0 m/s/s for g.

See if you can make sense of all the different perspectives on energy. Note that, because all parts of the system start from rest, the initial kinetic energies are not shown (all are zero). In some views, you see the work done by gravity on block 1 and/or block 2, or the work done by tension on block 1, block 2, or on the pulley. The labels are either above or below the bars, not beside them. U is gravitational potential energy, W is work, and K is kinetic energy.

Simulation first posted on 8-30-2016. Written by Andrew Duffy

Creative Commons License
This work by Andrew Duffy is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
This simulation can be found in the collection at

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