Explanation:
Rest and motion are relative terms. A body at rest with respect to one observer may be in motion with respect to another observer. For example a person sitting in a moving train is at rest with respect to the train.
Answer:

Explanation:
Given:
mass of the wire, 
length of the wire, 
current in the wire, 
Now form the Lorentz force we know that every current carrying wire experiences a magnetic force on it due to the magnetic field components perpendicular to it.
Mathematically given as:


here: we nee to balance the gravitational force on the mass.
magnetic field


This magnetic field must be perpendicular to the direction of current in the wire and the these two directional quantities must lie in a plane normal to the direction of gravity according to the Fleming's left hand rule.
Well, the relationship between the net force and mass and acceleration of an object are directly related, as per the equation - Fnet = ma.
Thus the solution is A. As the net force of an object decreases, the object's acceleration also decreases, mass is kept constant.
Answer:
In an elastic collision, the momentum is conserved and the mechanical energy is conserved too.
Explanation:
There are two types of collisions:
- Elastic collision: in an elastic collision, the total momentum before and after the collision is conserved; also, the total mechanical energy before and after the collision is conserved.
- Inelastic collision: in an inelastic collision, the total momentum before and after the colllision is conserved, while the total mechanical energy is not conserved (in fact, part of the energy is converted into other forms of energy such that thermal energy, due to the presence of frictional forces)