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slava [35]
4 years ago
12

A certain 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
Physics
1 answer:
skelet666 [1.2K]4 years ago
8 0

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.

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Nana76 [90]
What's is the question asking, true or false?
5 0
3 years ago
Object 1 of mass m moves with speed v in the positive direction. Object 2 of mass 3 m moves with speed 4 v in the negative x-dir
Klio2033 [76]

Answer:

This means that the kinetic energy of second object is 48times that of the first object

Explanation:

Kinetic energy is the energy possessed by a body by virtue of its motion e.g motion of an accelerating car. Mathematically,

Kinetic energy = 1/2mv² where;

m is the mass of the object

v is the velocity of the object

If Object 1 of mass m moves with speed v in the positive direction, its kinetic energy will be expressed as;

K1 = 1/2mv²

For Object 2 of mass 3m moving with speed 4v in the negative x-direction, its kinetic energy can be expressed as;

K2 = 1/2(3m)(4v)²

K2 = 1/2(3m)(16v²)

K2 = (3m)(8v²)

K2 = 24mv²

To compare the kinetic energy of both bodies, we will take the ratio of K2:K1 to have;

K2/K1 = 24mv²/(1/2)mv²

K2/K1 = 24/(1/2)

K2/K1 = 48

K2 = 48K1

This means that the kinetic energy of second object is 48times that of the first object and moving in the negative x direction since the body of mass 3m initially moves in the negative x direction.

3 0
4 years ago
Which best explains why no current is induced? The wire needs to be coiled less tightly. The wire needs to be straight, not coil
Ann [662]
The magnet needs to be held above the coils of wires

7 0
4 years ago
Read 2 more answers
A 5 kg
kotykmax [81]

Answer:

<em>The object-Earth system is open</em>

F_n=ma=5\ (7.2)=36\ N

Explanation:

<u>Accelerated Motion </u>

When an object is released in free air (with no other forces than the gravity), it describes a free-fall motion and the formulas include the acceleration of gravity as part of the calculations. But when there is another external force, then the acceleration is not the gravity, but the result of the net force exerted on the mass of the object.

By definition, an open system includes the exchange of energy from and to the surroundings, that is why all systems surrounding our planet are considered as open systems. In our case, the object is interacting with the planet's gravity and there is some other external force, which will be computed later. The object-Earth system is open.

If the object starts from rest, its initial speed is zero, and

v_f=a\ t

where a is the acceleration and t is the time. The distance traveled is given by :

\displaystyle y=\frac{a\ t^2}{2}

From the two above equations, we find that:

v_f^2=2ay

Solving for a

\displaystyle a=\frac{v_f^2}{2y}

\displaystyle a=\frac{12^2}{2\ (10)}

a=7.2\ m/s^2

It means the net force is

F_n=ma=5\ (7.2)=36\ N

The object's weight is

W=5\ (9.8)=49 N

This means there is some external force acting upwards delaying the object's fall of a magnitude of

F_e=49-36=13\ N

3 0
3 years ago
When a man returns to his well-sealed house on a summer day, he finds that the house is at 35°C. He turns on the air conditioner
Paul [167]

Answer:

1353.38 Watt

Explanation:

T₁ = Initial temperature of the house = 35°C

T₂ = Final temperature of the house = 20°C

Δt = Time taken to cool the house = 38 min = 38×60 = 2280 s

m = mass of air in the house = 800 kg

Cv = Specific heat at constant volume = 0.72 kJ/kgK

Cp = Specific heat at constant pressure = 1.0 kJ/kgK

Heat removed

q = mCvΔT

⇒q = 800×720×(35-20)

⇒q = 8640000 J

Average rate of hear removal

Q=\frac{q}{\Delta t}\\\Rightarrow Q=\frac{8640000}{2280}\\\Rightarrow Q=3789.47\ W

COP=\frac{Q}{W}\\\Rightarrow W=\frac{Q}{COP}\\\Rightarrow W=\frac{3789.47}{2.8}\\\Rightarrow W=1353.38\ W

∴ Power drawn by the air conditioner is 1353.38 Watt

6 0
3 years ago
Read 2 more answers
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