How would you present weight change if earth had twice the mass that it does now

It would double. g = GM/r^2 where G is the gravitational constant, M is the mass of the Earth, and r is the radius of the Earth. So, if the Earth's mass doubled, g would double, therefore, so would your weight

thermal energy is the answer

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