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it takes a force of 46 kN on the lead car of a 16-car passenger train with mass

ID: 1462750 • Letter: I

Question

it takes a force of 46 kN on the lead car of a 16-car passenger train with mass 9.1×105kg to pull it at a constant 42 m/s on level tracks.

1)What power must the locomotive provide to the lead car?

2)How much more power to the lead car than calculated in part A would be needed to give the train an acceleration of 1.2 m/s2 , at the instant that the train has a speed of 42 m/s on level tracks?

3)How much more power to the lead car than that calculated in part A would be needed to move the train up a 1.5% grade (slope angle =arctan 0.015) at a constant 42 m/s ?

Explanation / Answer

1) Power provided by the locomotive, P = F*v

= 46*10^3*42

= 1932000 Watts

2) extra power provided = F'*v

= m*a*v

= 9.1*10^5*1.2*42

= 45864000 W

3) alfa = tan^-1(0.015)

= 0.8594 degrees

extra power provided = F'*v

= m*g*sin(alfa)*v

= 9.1*10^5*9.8*sin(0.8594)*42

= 5617890 W