Because you have to study about electricity, first of all, and also need to study about polarity
The 5kg object 5m/s 1 m off the ground
It would need to be over 20 because if the load of the Pulley E is 20 and the effort is 20, then they will be equal and the Pulley would not move, so your answer is at least 20
Answer:
Approximately 18 volts when the magnetic field strength increases from
to
at a constant rate.
Explanation:
By the Faraday's Law of Induction, the EMF
that a changing magnetic flux induces in a coil is:
,
where
is the number of turns in the coil, and
is the rate of change in magnetic flux through this coil.
However, for a coil the magnetic flux
is equal to
,
where
is the magnetic field strength at the coil, and
is the area of the coil perpendicular to the magnetic field.
For this coil, the magnetic field is perpendicular to coil, so
and
. The area of this circular coil is equal to
.
doesn't change, so the rate of change in the magnetic flux
through the coil depends only on the rate of change in the magnetic field strength
. The size of the magnetic field at the instant that
will not matter as long as the rate of change in
is constant.
.
As a result,
.
The question is poor.
It expects you to choose 'B', but things aren't nearly that simple.
We picture all of the asteroids bunched up in a neat bunch between
the orbits of Mars and Jupiter, with each asteroid following its own
nearly circular orbit. But many asteroids have wildly non-circular
'eccentric' orbits, sometimes being closer to the sun than the Earth is.
You know how you hear so much discussion about when did the Earth
get hit by an asteroid ? and when will the Earth be hit by another asteroid ?
and what will happen when the Earth is hit by an asteroid again ? None
of that would be possible if asteroids all had nearly circular orbits.
We picture comets as having these loooong skinny orbits, spending
most of every orbit waaay out in the solar system, and then dipping
close to the sun for a few days, and then going back waaaay out again.
But there are also many comets in nearly circular orbits around the sun.
You never hear anything about them, because you can never see them
without a powerful telescope, and they never do anything exciting.
So some comets could be a correct answer to this question too.
And since meteoroids are the remains of old comets, and follow the
orbit of the comet that they chipped off from, there are a lot of meteoroids
in circular orbits too, and they could also be a correct answer to this question.