b
થતું કાર્ય વિરુદ્ધમાં લાગતું બળ \({\text{F}}\,\, = \,\,{\text{mg}}\,{\text{sin}}\,\theta \,\, = \,\,{\text{10000}}\,\,\, \times \,\,{\text{10}}\,\, \times \,\,\frac{{\text{1}}}{{{\text{50}}}}\,\, = \,\,2000\,\,N\)

વેગ \({\text{v}}\,\, = \,\,\frac{{{\text{36}}\,\, \times \,\,{\text{5}}}}{{{\text{18}}}}\,\, = \,\,10\,m/s\) 

તેથી,  \(\,{\text{P}}\,\, = \,\,{\text{2000}}\,\, \times \,\,{\text{10}}\,\, = \,\,{\text{20}}\,\,{\text{kW}}\)