Which is a better conductor, a flagpole or a flag? Why?

A satellite revolves around a planet at an altitude equal to the radius of the planet. the force of gravitational interaction be

USPshnik [31]

f2 = f0/4 The gravity from the planet can be modeled as a point source at the center of the planet with all of the planet's mass concentrated at that point. So the initial condition for f0 has the satellite at a distance of 2r, where r equals the planet's radius. The expression for the force of gravity is F = G*m1*m2/r^2 where F = Force G = Gravitational constant m1,m2 = masses involved r = distance between center of masses. Now for f2, the satellite has an altitude of 3r and when you add in the planet's radius, the distance from the center of the planet is now 4r. When you compare that to the original distance of 2r, that will show you that the satellite is now twice as far from the center of the planet as it was when it started. So let's compare the gravitational attraction, before and after. f0 = G*m1*m2/r^2 f2 = G*m1*m2/(2r)^2 f2/f0 = (G*m1*m2/(2r)^2) / (G*m1*m2/r^2) The Gm m1, and m2 terms cancel, so f2/f0 = (1/(2r)^2) / (1/r^2) f2/f0 = (1/4r^2) / (1/r^2) And the r^2 terms cancel, so f2/f0 = (1/4) / (1/1) f2/f0 = (1/4) / 1 f2/f0 = 1/4 f2 = f0*1/4 f2 = f0/4 So the gravitational force on the satellite after tripling it's altitude is one fourth the original force.

6 0

1 year ago

Why is the following situation impossible? Two identical dust particles of mass 1.00 µg are floating in empty space, far from an

Igoryamba

Answer:

This is a conceptual problem so I will try my best to explain the impossible scenario. First of all the two dust particles ara virtually exempt from any external forces and at rest with respect to each other. This could theoretically happen even if it's difficult for that to happen. The problem is that each of the particles have an electric charge which are equal in magnitude and sign. Thus each particle should feel the presence of the other via a force. The forces felt by the particles are equal and opposite facing away from each other so both charges have a net acceleration according to Newton's second law because of the presence of a force in each particle:

$a=\frac{F}{m}$

Having seen Newton's second law it should be clear that the particles are actually moving away from each other and will not remain at rest with respect to each other. This is in contradiction with the last statement in the problem.

4 0

1 year ago

An automatic coffee maker uses a resistive heating element to boil the 2.4 kg of water that was poured into it at 21 °C. The cur

MariettaO [177]

Answer:

Explanation:

The expression for the calculation of the enthalpy change of a process is shown below as:-

$\Delta H=m\times C\times \Delta T$

Where,

$\Delta H$

is the enthalpy change

m is the mass

C is the specific heat capacity

$\Delta T$

is the temperature change

Thus, given that:-

Mass of water = 2.4 kg

Specific heat = 4.18 J/g°C

$\Delta T=100-21\ ^0C=79\ ^0C$

So,

$\Delta H=2.4\times 4.18\times 79\ J=792.52\ kJ$

Heat Supplied $Q=VIt$

where $i=current$

$V=Voltage$

$8.5\times 120\times t=2.4\times 4186\times 79$

$t=778.10 s$

6 0

2 years ago

Which statement about energy conservation BEST explains why a bouncing basketball will not remain in motion forever?

bearhunter [10]

Answer: d

Explanation:

7 0

2 years ago

Assume the motions and currents mentioned are along the x axis and fields are in the y direction. (a) does an electric field exe

matrenka [14]

(a) does an electric field exert a force on a stationary charged object?
Yes. The force exerted by an electric field of intensity E on an object with charge q is
 $F=qE$
As we can see, it doesn't depend on the speed of the object, so this force acts also when the object is stationary.

(b) does a magnetic field do so?
No. In fact, the magnetic force exerted by a magnetic field of intensity B on an object with charge q and speed v is
 $F=qvB \sin \theta$
where $\theta$ is the angle between the direction of v and B.
As we can see, the value of the force F depends on the value of the speed v: if the object is stationary, then v=0, and so the force is zero as well.

(c) does an electric field exert a force on a moving charged object?
Yes, The intensity of the electric force is still
 $F=qE$
as stated in point (a), and since it does not depend on the speed of the charge, the electric force is still present.

(d) does a magnetic field do so?
Yes. As we said in point b, the magnetic force is
$F=qvB \sin \theta$
And now the object is moving with a certain speed v, so the magnetic force F this time is different from zero.

(e) does an electric field exert a force on a straight current-carrying wire?
Yes. A current in a wire consists of many charges traveling through the wire, and since the electric field always exerts a force on a charge, then the electric field exerts a force on the charges traveling through the wire.

(f) does a magnetic field do so?
Yes. The current in the wire consists of charges that are moving with a certain speed v, and we said that a magnetic field always exerts a force on a moving charge, so the magnetic field is exerting a magnetic force on the charges that are traveling through the wire.

(g) does an electric field exert a force on a beam of moving electrons?
Yes. Electrons have an electric charge, and we said that the force exerted by an electric field is
 $F=qE$
So, an electric field always exerts a force on an electric charge, therefore on an electron beam as well.

(h) does a magnetic field do so?
Yes, because the electrons in the beam are moving with a certain speed v, so the magnetic force
 $F=qvB \sin \theta$
is different from zero because v is different from zero.

6 0

2 years ago