Question

An automobile having a mass of 884 kg initially moves along a level highway at 68 km/h relative to the highway. It then climbs a hill whose crest is 69 m above the level highway and parks at a rest area located there. For the automobile, determine its changes in kinetic energy, in kJ

Answer 1

ΔK.E. = - 142.72 kJ

Step-by-step explanation:

mass = 884 kg

initial velocity = 68 km/h = 68 \times \frac {5}{18} = 18.89 m/s

final velocity = 0 m/s

height = 69 m

change in kinetic energy :

ΔK.E. =
`(1)/(2)m(v_f^2-v_i^2)`

ΔK.E. =
`(1)/(2)* 884 * (0^2-18.89^2)`

ΔK.E. =-142,716.05 J

ΔK.E. =-142.72 kJ

hence change in kinetic energy of the automobile is -142.72 kJ