1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Fynjy0 [20]
3 years ago
11

12. The resistivity of a given wire of cross-sectional

Physics
1 answer:
luda_lava [24]3 years ago
3 0

R = resistivity × (l/A), A = πr^2= πd^2/4

2 =( 4.9 × 10^ -4) * (l/π0.7^2/4)

make l the subject and calculate.

i assumed we are looking for the length if the wire.

You might be interested in
A bicycle wheel has spokes for support. Each spoke extends from the center of the wheel to the rim. Which method can be used to
hoa [83]
Since the formula for the circumference of a circle is pi x d or pi x 2r. The radius is a straight line from the center of the circle to the outer part of it, which is exactly what the spokes are to the wheel. So we take the length of the spoke, which is the radius, and use it in our equation. pi times 2 times the length of the spoke will give us our answer.
3 0
3 years ago
Read 2 more answers
Which trait is determined entirely by heredity ?
quester [9]
Shape of the nose is entirely hereditary, as genes have nothing to do with any of the other attributes.
7 0
3 years ago
Read 2 more answers
Is it possible to have a charge of 5 x 10-20 C? Why?
ruslelena [56]

1) No

2) Yes

3) No

4) Equal and opposite

5) 32400 N

6) Repulsive

7) The electric force is 2.3\cdot 10^{39} times bigger than the gravitational force

Explanation:

1)

In nature, the minimum possible charge that an object can have is the charge of the electron, which is called fundamental charge:

e=1.6\cdot 10^{-19}C

Electrons are indivisible particles (they cannot be separated), this means that an object can have at least the charge equal to the charge of one electron (in fact, it cannot have a charge less than e, because it would meant that the object has a "fractional number" of electrons).

In this problem, the object has a charge of

Q=5\cdot 10^{-20}C

If we compare this value to e, we notice that Q, so no object can have a charge of Q.

2)

As we said in part 1), an object should have an integer number of electrons in order to be charged.

This means that the charge of an object must be an integer multiple of the fundamental charge, so we can write it as:

Q=ne

where

Q is the charge of the object

n is an integer multiple

e is the fundamental charge

Here we have

Q=2.4\cdot 10^{-18}C

Substituting the value of e, we find n:

n=\frac{Q}{e}=\frac{2.4\cdot 10^{-18}}{1.6\cdot 10^{-19}}=15

n is integer, so this value of the charge is possible.

3)

We now do the same procedure for the new object in this part, which has a charge of

Q=2.0\cdot 10^{-19}C

Again, the charge on this object can be written as

Q=ne

where

n is the number of electrons in the object

Using the value of the fundamental charge,

e=1.6\cdot 10^{-19}C

We find:

n=\frac{Q}{e}=\frac{2.0\cdot 10^{-19}}{1.6\cdot 10^{-19}}=1.25

n is not integer, so this value of charge is not possible, since an object cannot have a fractional number of electrons.

4)

To solve this part, we use Newton's third law of motion, which states that:

"When an object A exerts a force on an object B (Action force), then object B exerts an equal and opposite force on object A (reaction force)".

In this problem, we have two objects:

- A charge Q

- A charge 5Q

Charge Q exerts an electric force on charge 5Q, and we can call this action force. At the same time, charge 5Q exerts an electric force on charge Q (reaction force), and according to Newton's 3rd law, the two forces are equal and opposite.

5)

The magnitude of the electric force between two single-point charges is

F=k\frac{q_1 q_2}{r^2}

where

k is the Coulomb's constant

q1, q2 are the two charges

r is the separation between the two charges

In this problem we have:

q_1=+4.5\cdot 10^{-6}C is charge 1

q_2=+7.2\cdot 10^{-6}C is charge 2

r = 0.30 cm = 0.003 m is the separation

So, the electric force  between the two charges is

F=(9\cdot 10^9)\frac{(4.5\cdot 10^{-6})(7.2\cdot 10^{-6})}{(0.003)^2}=32400 N

6)

The electric force between two charged objects has direction as follows:

- If the two objects have charges of opposite signs (+ and -), the force between them is attractive

- If the two objects have charges of same sign (++ or --), the force between them is repulsive

In this problem, the two charges are:

q_1=+4.5\cdot 10^{-6}C is charge 1

q_2=+7.2\cdot 10^{-6}C is charge 2

We see that the two charges have same sign: therefore, the force between them is repulsive.

7)

The electric force between the proton and the electron in the atom can be written as

F_E=k\frac{q_1 q_2}{r^2}

where

q_1 = q_2 = e = 1.6\cdot 10^{-19}C is the magnitude of the charge of the proton and of the electron

r=5.3\cdot 10^{-11} m is the separation between them

So the force can be rewritten as

F_E=\frac{ke^2}{r^2}

The gravitational force between the proton and the electron can be written as

F_G=G\frac{m_p m_e}{r^2}

where

G is the gravitational constant

m_p = 1.67\cdot 10^{-27}kg is the proton mass

m_e=9.11\cdot 10^{-27}kg is the electron mass

Comparing the 2 forces,

\frac{F_E}{F_G}=\frac{ke^2}{Gm_p m_e}=\frac{(9\cdot 10^9)(1.6\cdot 10^{-19})^2}{(6.67\cdot 10^{-11})(1.67\cdot 10^{-27})(9.11\cdot 10^{-31})}=2.3\cdot 10^{39}

8 0
3 years ago
Which of the following is an example of kinetic energy being converted to potential energy?
horsena [70]
Of the following...?? Is there more to this question? :)
4 0
2 years ago
Read 2 more answers
HELP ASAP PLEASEEEEEEEEEEEE
ira [324]
It's the second graph!
it's the only one with a negative gradient.
so the temperature of the ball will fall in water as it looses its heat.

activate windows,:-P
8 0
3 years ago
Other questions:
  • Auroras occur in the _______. a. troposphere b. stratosphere c. mesosphere d. thermosphere
    9·2 answers
  • Which of the following actions is best understood using Einstein's concepts rather than Newtonian physics?
    10·2 answers
  • For a molecule of O2 at room temperature (300 K), calculate the average angular velocity for rotations about the x or y axes. Th
    11·1 answer
  • Dalila plans an experiment to examine plant growth. She
    6·2 answers
  • In an emergency, a driver brings a car to a full stop in 5.0s. The car is traveling at a rate of 38m/s when the breaking begins.
    14·1 answer
  • Based electromagnetic spectrum? on its surface temperature of 6,000 K, most photons that leave the Sun's surface lie in which re
    9·1 answer
  • A 55-kg skier starts from rest at the top of a ski jump, point A in Fig. 6–48, and travels down the ramp. If fric- tion and air
    14·2 answers
  • When heat is added to a substance, describe how the molecules are affected. Use the words kinetic energy and potential energy ap
    7·1 answer
  • In this picture there is a circuit and the boxes are circuit component please tell how many nodes are there in circuit?
    8·1 answer
  • when a metal sphere is dropped in to a tall cylinder containing liquid its acceleration is g÷2 (gravity over 2) show that : dens
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!