Which of the following is true about high-energy mechanical devices? They usually need to be kept warm in order to preserve mechanical energy
They usually need to be cooled to dissipate thermal energy build-up and prevent damage.
They usually convert radiant energy into electrical energy
During an energy conversion, none of the energy is transferred as thermal energy because the devices are free of friction.

They usually need to be cooled to dissipate thermal energy build-up and prevent damage :}

Explanation:

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min