A train with a total mass of 1.1 × 106 kg rises 819 m while traveling a distance

Question

A train with a total mass of 1.1 × 106 kg rises
819 m while traveling a distance of 75 km at
an average speed of 9 km/h. The frictional
force is 0.8 percent of the weight.
Find the kinetic energy of the train. The
acceleration of gravity is 9.81 m/s2 .
Answer in units of MJ
75 km = 75e3 m or 75,000 m


a) 3.437 MJ or 3.437e6 or 3.437 x 10^6

b) Find the total change in its potential energy.
Answer in units of J
answer is 8.828e9 or 8.828 x 10^9

c) Find the energy dissipated by friction.
Answer in units of J

answer is not 1.1175e10

Explanation / Answer

a ) K.E = 1/2 * M *V^2
= 1/2 * 1.1 * 10^6 * (2.5)^2
= 2784375 J
= 2.784375 MJ

b ) change in P.E = mgh
= 1.1 * 10^6 * 9.8 * 819
= 8828820000 J
= 8828.2 MJ

c ) energy dissipated by friction
friction force * distance
friction force = 0.8% of Mg

= (0.8/100) * 1.1 * 10^6 * 9.8

= 86240 N

energy dissipated = (86240 * 75000 )
= 6468,000,000 J

= 6.468 * 10^9 J

hope now its correct

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