Can you Help with these 2 Questions? An object whose mass is 400 kg is located a

Question

Can you Help with these 2 Questions?

An object whose mass is 400 kg is located at an elevation of 25 m above the surface of the earth. For g = 9.78 m/s2, determine the gravitational potential energy of the object, in kJ. relative to the surface of the earth. An automobile having a mass of 900 kg initially moves along a level highway at 100 km/h relative to the highway. It then climbs a hill whose crest is 50 m above the level highway and parks at a rest area located there. For the automobile, determine its changes in kinetic and potential energy, each in kJ. For each quantity kinetic energy and potential energy, specify your choice of datum and reference value at that datum. Let g = 9.81 m/s2.

Explanation / Answer

a.) PE = mgh = 400*9.78*25 = 97.8 kJ

B.) Let reference surface be theroad

KE = 1/2mv^2 = 1/2*900*(100*1000/3600)^2 = 347.22kJ

PE = mgh = 900*9.81*50 = 441.45kJ

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