A 397 kg piano is being lifted at a steady speed from ground level straight up to an apartment 19.7 m above the ground. The crane that is doing the lifting produces a steady power of 413 Watts. How much time does it take to lift the piano?
+33666 Energy required to lift piano to apartment is 397*9.81*19.7 Joules (where acceleration of gravity is 9.81ms-2)
Power available = 413 Watts = 413 Joules/second, so
Time taken = 397*9.81*19.7/413 seconds
$${\mathtt{TimeTaken}} = {\frac{{\mathtt{397}}{\mathtt{\,\times\,}}{\mathtt{9.81}}{\mathtt{\,\times\,}}{\mathtt{19.7}}}{{\mathtt{413}}}} = {\mathtt{TimeTaken}} = {\mathtt{185.770\: \!046\: \!004\: \!842\: \!615}}$$seconds
+33666 Energy required to lift piano to apartment is 397*9.81*19.7 Joules (where acceleration of gravity is 9.81ms-2)
Power available = 413 Watts = 413 Joules/second, so
Time taken = 397*9.81*19.7/413 seconds
$${\mathtt{TimeTaken}} = {\frac{{\mathtt{397}}{\mathtt{\,\times\,}}{\mathtt{9.81}}{\mathtt{\,\times\,}}{\mathtt{19.7}}}{{\mathtt{413}}}} = {\mathtt{TimeTaken}} = {\mathtt{185.770\: \!046\: \!004\: \!842\: \!615}}$$seconds
