question_answer

How many 2.5 kg bricks can a man carry up a stair 3.6 m high in one hour, if he works at the average rate of 9.8 watt?

Answer:

\[n=?\] \[m=2.5\,kg\] \[h=3.6\,m\] \[t=1\,hour=60\times 60\sec \] \[P=9.8\,w\] \[g=9.8\,m/{{s}^{2}}\] \[P=\frac{mgh}{t}=\frac{nmgh}{t}\] \[\Rightarrow h=\frac{9.8\times 60\times 60}{2.5\times 9.8\times 3.6}=400\]