To solve this problem we will apply the concepts related to momentum and momentum on a body. Both are equivalent values but can be found through different expressions. The impulse is the product of the Force for time while the momentum is the product between the mass and the velocity. The result of these operations yields equivalent units.
PART A ) The Impulse can be calculcated as follows

Where,
F = Force
Change in time
Replacing,


PART B) At the same time the momentum follows the conservation of momentum where:
Initial momentum= Final momentum
And the change in momentum is equal to the Impulse, then

And

There is not initial momentum then



Answer:
Radius, r = 0.00523 meters
Explanation:
It is given that,
Magnetic field, 
Current in the toroid, I = 9.6 A
Number of turns, N = 6
We need to find the radius of the toroid. The magnetic field at the center of the toroid is given by :

r = 0.00523 m
or

So, the radius of the toroid is 0.00523 meters. Hence, this is the required solution.
It stops accelerating when the air resistance is equal to its weight.
That's (m•g)
= (2 kg) • (9.8 m/s^2)
= 19.6 newtons
Answer:
ΔS total ≥ 0 (ΔS total = 0 if the process is carried out reversibly in the surroundings)
Explanation:
Assuming that the entropy change in the aluminium bar is due to heat exchange with the surroundings ( the lake) , then the entropy change of the aluminium bar is, according to the second law of thermodynamics, :
ΔS al ≥ ∫dQ/T
if the heat transfer is carried out reversibly
ΔS al =∫dQ/T
in the surroundings
ΔS surr ≥ -∫dQ/T = -ΔS al → ΔS surr ≥ -ΔS al = - (-1238 J/K) = 1238 J/K
the total entropy change will be
ΔS total = ΔS al + ΔS surr
ΔS total ≥ ΔS al + (-ΔS al) =
ΔS total ≥ 0
the total entropy change will be ΔS total = 0 if the process is carried out reversibly in the surroundings
Answer:
Entropy is increasing. Entropy is decreasing.
Explanation:
The Entropy doesn't change.