Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
An iron cube whose mass is m slides horizontally over a long iron plate.
The mass of the plate M is much larger than m. The plate is a rest while
the cube has an initial kinetic energy K. Friction brings the cube to
rest before its base reaches the plate's boundary. Everything is in the
vacuum and the thermal energy, dU, added to both pieces of iron is not
radiated. [In principle, dU can be calculated from the observed change of
temperature but no thermometer is available.] Which of the following is
correct and why?
1. The thermal energy change, dU, is equal to K.
2. Only part of K goes into dU, the rest is used to do work W=3DR*x, where
R is the force of kinetic friction and x is the distance the cube
slides before comming to rest.
3. Neither of the above is correct.
I am really confused in this situation. My frame of reference (for K and x)
is attached to the plate.
Make sure I understand you.