Answer:
Zero
Explanation:
It is given that,
A person swims to the other end of a 20m long pool and back.
We need to find his displacement.
Displacement = shortest path covered
He reaches at the same position as from where he has started. It means the shortest path covered is equal to 0 i.e. his displacement is zero.
Answer:
If the particle is an electron 
If the particle is a proton, 
Explanation:
Initial speed at the origin, 
to +ve x-axis
The particle crosses the x-axis at , x = 1.5 cm = 0.015 m
The particle can either be an electron or a proton:
Mass of an electron, 
Mass of a proton, 
The electric field intensity along the positive y axis
, can be given by the formula:

If the particle is an electron:



If the particle is a proton:



Answer:
North pole
Explanation:
According to the law of magnetism:
<em>Unlike poles attract while like poles repel</em>
Since the south pole of the steel is brought near the nail, and the nail is meant to attract the steel magnet, the nail domain realigns itself to produce a pole opposite to the pole of the steel magnet brought near it.
Since the North pole is the opposite of the south pole, the North pole will be at the pointed end of the nail so that it can attract the steel magnet.