B is the answer for your question the answer is b an elevator slowing down
Answer:
Magnetic field, B = 0.042 T
Explanation:
It is given that,
Speed of charged particle, 
Angle between velocity and the magnetic field, 
Charge, 
Magnetic force, F = 0.002 N
The magnetic force is given by :

B is the magnetic field


B = 0.042 T
So, the strength of the magnetic field is 0.042 Tesla. Hence, this is the required solution.
Answer:

Explanation:
As we know that train is initially moving with the speed

now we know that

now the final speed of the train when it crossed the crossing


now we can use kinematics here



Now the time to cross that junction is given as



Answer:
The period is
Explanation:
From the question we are told that
The mass is 
The extension of the spring is 
The spring constant for this is mathematically represented as

Where F is the force on the spring which is mathematically evaluated as


So


The period of oscillation is mathematically evaluated as
substituting values