Physics
posted by Me on .
A train on a mountain railway is carrying 200 people of average mass 70kg up a slope at an angle of 30° to the horizontal and at a speed of 6.0 m s–1. The train itself has a mass of 80 000 kg. The percentage of the power from the engine which is used to raise the passengers and the train is 40%.
What is the power of the engine?

Power=Mg(speed)*sin(θ)/0.40 watts
M=total mass (passengers, train, etc.) 
mass of passengers=200*70=14000...total mass of train +passengers=80000+14000... their weight =94000*9.81=922140..now force = mgsin30= 922140sin30=461070.. power =force*velocity= 461070*6=2766420..this is power output.. now we know that power output divide by power input *100%=40%..solve it to get the answer 6.9MW...