Kinetic energy question.....

Question

(a) What is the kinetic energy in joules of a 930-kg automobile traveling at 70 km/h?
___ J

(b) How much work would have to be done to bring a 930-kg automobile traveling at 70 km/h to a stop?
___ J

Answer 1

v = 70 (1000 m/km)/(3600 s/h) = 19.44 m/s

 

K.E = 1/2 m v² = 1/2 (950) (19.44)² = W done

 

=179,509 J

 

From conservation of energy, Work done is equal to the loss in kinetic energy as there is no change in potential energy