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- Homework Statement
- Object A is stationary while objects B and C are in motion. Forces from object A do 10 J of work on object B and -5 J of work on object C. Forces from the environment do 4J of work on object B and 8 J of work on object C. Objects B and C do not interact. What are delta K_tot and delta U_int if one system is defined to include objects A, B, and C and their interactions?

- Relevant Equations
- delta E = external work = delta K_tot + delta_U

W_ext is the external work done on B and C, which is 12 J

Delta K_tot is the internal work, which is the work done by A on B plus the work done by A on C

Delta K_tot = 5

Solving for \Delta U, we find that the change in potential energy is 7 J

This answer says otherwise: https://www.studysmarter.us/textboo...tionary-while-objects-are-in-motion-forces-f/

If Delta K_tot is not W_int, and instead delta U_int is -W_int, then W_int = 5 would imply delta U_int = -5

Delta K_tot is the internal work, which is the work done by A on B plus the work done by A on C

Delta K_tot = 5

Solving for \Delta U, we find that the change in potential energy is 7 J

This answer says otherwise: https://www.studysmarter.us/textboo...tionary-while-objects-are-in-motion-forces-f/

If Delta K_tot is not W_int, and instead delta U_int is -W_int, then W_int = 5 would imply delta U_int = -5

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