Answer:
4 A
Explanation:
The relationship between current, voltage and resistance in a circuit is given by Ohm's law:

where
V is the voltage
R is the resistance
I is the current
The equation can also be rewritten as

from which we see that the current is inversely proportional to the resistance, R.
In this problem, the initial current is I = 8 A. Then the resistance is doubled:
R ' = 2R
So the new current is

so the current is halved.
Answer:
extreme heat, because no physical damage can demagnetize a magnet
Explanation:
To solve this problem we will apply the concepts related to the conservation of momentum. This can be defined as the product between the mass and the velocity of each object, and by conservation it will be understood that the amount of the initial momentum is equal to the amount of the final momentum. By the law of conservation of momentum,

Here,
= Mass of Basketball
= Mass of Tennis ball
= Initial velocity of Basketball
= Initial Velocity of Tennis ball
= Final velocity of Basketball
= Final velocity of the tennis ball
Replacing,

Solving for the final velocity of the tennis ball

Therefore the velocity of the tennis ball after collision is 11 m/s
Power = energy / time
Time should be in seconds
5 hours = 5 × 60 minutes = 5 × 60 ×60 seconds = 18000 s
Power = 6000/18000 = 0.333 W
Hope it helped!