Due to design changes, the efficiency of an engine increases from 0.28 to 0.51. for the same input heat |qh|, these changes increase the work done by the more efficient engine and reduce the amount of heat rejected to the cold reservoir. find the ratio of the heat rejected to the cold reservoir for the improved engine to that for the original engine.

the ratio of the heat rejected to the cold reservoir for the improved engine to that for the original engine is 0.68

Explanation:

Given information

initial efficiency, η = 0.28

final efficiency, η = 0.51

ratio of the heat rejected = (1 - η)/(1 - η)

                                        = (1 - 0.51)/(1 - 0.28)

                                        = 0.68

thermal energy is the answer