Answer:
(a) The self inductance, L = 21.95 mH
(b) The energy stored, E = 4.84 J
(c) the time, t = 0.154 s
Explanation:
(a) Self inductance is calculated as;

where;
N is the number of turns = 1000 loops
μ is the permeability of free space = 4π x 10⁻⁷ H/m
l is the length of the inductor, = 45 cm = 0.45 m
A is the area of the inductor (given diameter = 10 cm = 0.1 m)

(b) The energy stored in the inductor when 21 A current ;

(c) time it can be turned off if the induced emf cannot exceed 3.0 V;

Answer:
Small sports car.
Explanation:
Lets take
mass of the small car = m
mass of the truck = M
As we know that when car collide with the massive truck then due to change in the moment of the car both car as well as truck will feel force.We also know that from Third law of Newton's ,it states that every action have it reaction with same magnitude but in the opposite direction.
Therefore
F = m a
a=Acceleration of the car

F= M a'
a'=Acceleration of the massive truck

Here given that M > m that is why a > a'
Therefore car will experiences more acceleration.
Electrons have a negative charge, so if you give away electrons, you give away negative charge, thus ending with a positive charge.