9.Remove the power supply, accurately recording the time. Stir the water once more and then record the final temperature of the water. 4. RESULTS4.1 EXPERIMENTAL DATATable ITime (m)Voltage (V)Current (A)26.61.546.61.566.61.586.51.475106.51.475126.51.5146.61.5166.61.475186.51.475206.51.475226.51.475
246.51.475266.51.475286.51.475306.51.4756.5333333331.483333333Mass of the empty inner cup of the calorimeter (m_c)77.42Mass of the inner cup containing water (m_c + m_w)323.46Effective mass of the water from step 4 in the procedure (m'_w)Voltage (V)6.533333333Current (I)1.483333333Power (P=IV)9.691111111Time (t)1800Total electrical energy provided to system (E=Pt)17444Water initial temperature (T_i)18Water final temperature (T_f)32Total heat gained by the system (Q=m'_w*c_w(T_f-T_i)+m'_w*c_w(T_f-T_i))3994.21Electrical equivalent of heat (Je=E/Q)4.3673216984.3 ERROR ANALYSIS/5.DISCUSSION1.The mechanical equivalent of heat was a concept that had an important part in the development and acceptance of the conservation of energy. The concept stated that motion and heat are mutually interchangeable and that in every case, a given amount of work would generate the same amount of heat, provided the work done is totally converted to heat energy.2.Our experiment resulted with an electrical equivalent of heat of 4.367 J/cal. Our result was only slightly larger than the accepted value of 4.184 J/cal with a percent error of only4.38%. Errors could derive from human error when measuring the temperatures since they would not be 100% exact and when timing the stopwatch.
6. CONCLUSIONIn the lab, we proved that the total amount of energy in an isolated system remains constant over time. We showed that if the system is thermally isolated from surroundings, the total electrical energy delivered to the system should be equal to the total heat energy gained by the system.
You've reached the end of your free preview.
Want to read all 4 pages?
- Spring '16