Answer:
Final speed of boat + man is 1.66 m/s
Explanation:
As we know that there is no friction on the system or there is no external force on this system
So here we can use momentum conservation here

so we have
m = 85 kg
M = 135 kg
v = 4.30 m/s
now we have


Answer:
artificial: light bulb, flash light, computer screens. natural: sun, stars, fires.