Julius Blankenship
2022-09-13
Answered

Give examples of information that in a particular situation is: 1. relevant 2. irrelevant 3. reliable 4. unreliable 5. objective 6. biased 7. complete 8. incomplete 9. useful 10. useless 11. understandable 12. incomprehensible,

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asked 2021-02-21

Two small charged objects repel each other with a force F whenseparated by a distance d. if the charge on each object is reducedto one-fourth of its original value and the distance between themis reduced to d/2, the force becomes:

a) $\frac{F}{16}$

b) $\frac{F}{8}$

c) $\frac{F}{4}$

d) $\frac{F}{2}$

e)F

asked 2021-02-19

Two snowcats tow a housing unit to a new location at McMurdo Base, Antarctica, as shown in the figure. The sum of the forces $F}_{A$ and $F}_{B$ exerted on the unit by the horizontal cables is parallel to the line L, and ${F}_{A}=4200$ N. Determine $F}_{B$? Determine the magnitude of $F}_{A}+{F}_{B$?

asked 2021-01-31

A straight vertical wire carries a current of 1.20 A downward in a region b/t the poles of a large superconducting electromagnet,where the magnetic filed has magnitude B = 0.588 T and is horizontal. What are the magnitude and direction of the magnetic force on a 1.00 cm section of the wire that is in this uniform magnetic field, if the magnetic field direction is a) east? b)south? c) 30 degrees south of west?

According to the solutions, the force stays the same for parts $a,b,c:F=I\cdot l\cdot B=7.06\times {10}^{-3}$ but for part c,why isn't the 30 degree angle used to calculate the force?

asked 2021-02-25

A stream of water strikes a stationary turbine bladehorizontally, as the drawing illustrates. The incident water streamhas a velocity of +18.0 m/s, while the exiting water stream has avelocity of -18.0 m/s. The mass of water per second that strikesthe blade is 17.0 kg/s. Find themagnitude of the average force exerted on the water by theblade.

asked 2022-04-07

Is Magnetic force different in different frames?

Suppose a charged particle moves with a velocity $v$ near a wire carrying an electric current. So, a magnetic force acts on it. If the same particle is seen from a frame moving with velocity $v$ in the same direction, the charge will be found to be at rest. Will the magnetic force become zero in this frame? Will the magnetic field become zero in this frame?

Even though the solution says that the force shall be zero but the magnetic field will be independent of frame and henceforth exist, I am not convinced with the idea of zero force because even if I were to place myself in a frame moving with velocity $v$, I will see the particle executing a circular motion around a different center though. In reality I know that its the magnetic force that's causing it to move in a circle but in my frame if I say that there is no magnetic force, how would I explain the circular motion of the particle ?

Suppose a charged particle moves with a velocity $v$ near a wire carrying an electric current. So, a magnetic force acts on it. If the same particle is seen from a frame moving with velocity $v$ in the same direction, the charge will be found to be at rest. Will the magnetic force become zero in this frame? Will the magnetic field become zero in this frame?

Even though the solution says that the force shall be zero but the magnetic field will be independent of frame and henceforth exist, I am not convinced with the idea of zero force because even if I were to place myself in a frame moving with velocity $v$, I will see the particle executing a circular motion around a different center though. In reality I know that its the magnetic force that's causing it to move in a circle but in my frame if I say that there is no magnetic force, how would I explain the circular motion of the particle ?

asked 2022-05-18

Magnetic force between two point charges

I tried to derive the magnetic force between two point-charges for iterative computation. Starting out with Lorentz force and Biot–Savart law for a point charge.

$\overrightarrow{F}={q}_{2}(-\mathrm{\Delta}\overrightarrow{v}\times \overrightarrow{B})$

$\overrightarrow{B}=(\overrightarrow{\mathrm{\Delta}}v\times \overrightarrow{\mathrm{\Delta}}x)(\frac{{q}_{1}}{||\mathrm{\Delta}\overrightarrow{x}|{|}^{3}}\frac{{\mu}_{0}}{4\pi})$

And got this for the answer by direct subtitution:

$\overrightarrow{F}={q}_{2}(-\mathrm{\Delta}\overrightarrow{v}\times (\overrightarrow{\mathrm{\Delta}}v\times \overrightarrow{\mathrm{\Delta}}x)(\frac{{q}_{1}}{||\mathrm{\Delta}\overrightarrow{x}|{|}^{3}}\frac{{\mu}_{0}}{4\pi}))$

It does not seem to be right for several reasons.

1.It seems as if electron would be attracted to the nucleus by both magnetic and electrostatic force. Considering hydrogen atom.

2.It is possible to show that between non-moving particle and a non-moving wire with current in it should exist magnetic force. (Magnetic force acts between charge carriers in the wire and the point-charge. Non-moving particles in the wire do not have influence on the magnetic force)

Where have I gone wrong and how to find the correct expression for the magnetic force between two point-charges? Does the equation hold if $\mathrm{\Delta}v<<c$? If this equation proves to be wrong, what would be the correct approach?

I tried to derive the magnetic force between two point-charges for iterative computation. Starting out with Lorentz force and Biot–Savart law for a point charge.

$\overrightarrow{F}={q}_{2}(-\mathrm{\Delta}\overrightarrow{v}\times \overrightarrow{B})$

$\overrightarrow{B}=(\overrightarrow{\mathrm{\Delta}}v\times \overrightarrow{\mathrm{\Delta}}x)(\frac{{q}_{1}}{||\mathrm{\Delta}\overrightarrow{x}|{|}^{3}}\frac{{\mu}_{0}}{4\pi})$

And got this for the answer by direct subtitution:

$\overrightarrow{F}={q}_{2}(-\mathrm{\Delta}\overrightarrow{v}\times (\overrightarrow{\mathrm{\Delta}}v\times \overrightarrow{\mathrm{\Delta}}x)(\frac{{q}_{1}}{||\mathrm{\Delta}\overrightarrow{x}|{|}^{3}}\frac{{\mu}_{0}}{4\pi}))$

It does not seem to be right for several reasons.

1.It seems as if electron would be attracted to the nucleus by both magnetic and electrostatic force. Considering hydrogen atom.

2.It is possible to show that between non-moving particle and a non-moving wire with current in it should exist magnetic force. (Magnetic force acts between charge carriers in the wire and the point-charge. Non-moving particles in the wire do not have influence on the magnetic force)

Where have I gone wrong and how to find the correct expression for the magnetic force between two point-charges? Does the equation hold if $\mathrm{\Delta}v<<c$? If this equation proves to be wrong, what would be the correct approach?

asked 2022-09-24

Magnetic force and frames of reference

I'm having a hard time trying to understand the next situation:

Suppose that I have a magnet that creates a quite uniform magnetic filed $\overrightarrow{B}$. In the vicinity of this magnet there is a particle with charge $q$ that is moving with velocity $\overrightarrow{v}$ in some direction.

This is, in the frame of reference of the magnet, the particle is moving with velocity $\overrightarrow{v}$ and therefore the particle experiences a force given by: $\overrightarrow{F}=q\phantom{\rule{thinmathspace}{0ex}}(\overrightarrow{v}\times \overrightarrow{B})$. This would cause the path of the particle to curve around the magnetic field.

On the other hand, an observer situated in the particle would see the magnet moving with velocity ${\overrightarrow{v}}^{\prime}=-\overrightarrow{v}$. How would this observer account for the movement of the magnet caused by the force ${F}^{\prime}$?

I believe that the force ${\overrightarrow{F}}^{\prime}$ is given by the relativistic transformation:

${\overrightarrow{F}}^{\prime}=-\gamma \overrightarrow{F}$

Knowing that the force is perpendicular to the velocity (this is if, for instance, the particle is moving along the x axis, then the force is along the y axis).

I am in the early stages of understanding relativistic mechanics so please forgive me is the question looks silly. Thanks in advance.

I'm having a hard time trying to understand the next situation:

Suppose that I have a magnet that creates a quite uniform magnetic filed $\overrightarrow{B}$. In the vicinity of this magnet there is a particle with charge $q$ that is moving with velocity $\overrightarrow{v}$ in some direction.

This is, in the frame of reference of the magnet, the particle is moving with velocity $\overrightarrow{v}$ and therefore the particle experiences a force given by: $\overrightarrow{F}=q\phantom{\rule{thinmathspace}{0ex}}(\overrightarrow{v}\times \overrightarrow{B})$. This would cause the path of the particle to curve around the magnetic field.

On the other hand, an observer situated in the particle would see the magnet moving with velocity ${\overrightarrow{v}}^{\prime}=-\overrightarrow{v}$. How would this observer account for the movement of the magnet caused by the force ${F}^{\prime}$?

I believe that the force ${\overrightarrow{F}}^{\prime}$ is given by the relativistic transformation:

${\overrightarrow{F}}^{\prime}=-\gamma \overrightarrow{F}$

Knowing that the force is perpendicular to the velocity (this is if, for instance, the particle is moving along the x axis, then the force is along the y axis).

I am in the early stages of understanding relativistic mechanics so please forgive me is the question looks silly. Thanks in advance.