Acertain wire has a length l and a resistance r. it is stretched uniformly to a length of 2l. the resistance of the wire after it has been stretched is

I am not sure whether this is the right way to go about answering the question.

The resistance of a wire is proportional to its length, therefore doubling the length should double the resistance. But resistance is also proportional to the inverse square of the wire's cross-sectional area, and stretching the wire seems to imply increasing its length and decreasing its cross-sectional area, which would increase the resistance more than simply increasing its length.

I'll just say to only care about the effect of increasing the wire's length. Due to the wire's length now being 2l, the new resistance is 2r.

answer: question1

1,000 tons

question2

3: 8

question 3

store d

step-by-step explanation:

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.