Einstein's Theory of Relativity was a theory which carried about hesitation in Newton's gravity which was measured as an important part of science. Which brings one to query what we detect as being factual.
Freud's thoughts about the subliminal questions one's own mind to what we have faith in. Is a dream just a dream, or is it your subliminal trying to tell you a little? It brought about a feeling of being ignorant of what is going on in your own mind.
These and maybe other bring persons to doubt about the world about them and within themselves.
One way is the both have magnetic fields.
Answer:
Velocity after collision will be 20 m/sec
Explanation:
We have given mass of arrow 
Mass of arrow 
Mass of apple 
Apple is at rest so velocity of apple 
According to conservation of momentum
Momentum before collision is equal to momentum after collision
v = 20 m/sec
