Answer:
a differenceis that the string needs force to be used. without something pulling on it then it wont make the noise. meanwhile the pipe only needs air to be blow Wich can be caused naturally or intentionally
Given that,
Distance =30 m
speed = 0.5c
(A). We need to find the bell and siren simultaneous events for a passenger seated in the car
According to given data
The distance travelled by the light to reach either side of the rocket train car is same.
So, The two events are simultaneous and the bell and siren are the simultaneous events for a passenger seated in the car.
(B). We need to calculate time interval between the events
Using formula of time dilation
.....(I)
Where, 
= proper time
= time interval between the events
The time interval between the events measured in a reference frame
The proper time in this case is
For the second interval,
Put the value of 
in the equation (I)
Put the value in the equation
Negative sign shows the siren rings before the bell ring.
Hence, (A). Yes, the bell and siren are simultaneous events.
(B). The siren sounds before the bell rings.
Answer:
electronic communications may be disrupted
Explanation:
Solar Flares: They occur when the magnetic field lines carrying charged particle entangle and reorganize over the photosphere of the Sun. In these flares charged particles leave the surface of the Sun to travel outwards.
If these flares are directed towards Earth, they will interact with anything related to electricity and magnetism. Out of the given options third option is correct as the electronic communication will be disrupted. If the flares are strong a complete power blackout may occur and that would disrupt all the communication channel and power transmission. Such events have occurred in the past as well.
"Balanced" means that if there's something pulling one way, then there's also
something else pulling the other way.
-- If there's a kid sitting on one end of a see-saw, and another one with the
same weight sitting on the other end, then the see-saw is balanced, and
neither end goes up or down. It's just as if there's nobody sitting on it.
-- If there's a tug-of-war going on, and there are 300 freshmen pulling on one
end of a rope, and another 300 freshmen pulling in the opposite direction on
the other end of the rope, then the hanky hanging from the middle of the rope
doesn't move. The pulls on the rope are balanced, and it's just as if nobody
is pulling on it at all.
-- If a lady in the supermarket is pushing her shopping cart up the aisle, and her
two little kids are in front of the cart pushing it in the other direction, backwards,
toward her. If the kids are strong enough, then the forces on the cart can be
balanced. Then the cart doesn't move at all, and it's just as if nobody is pushing
on it at all.
From these examples, you can see a few things:
-- There's no such thing as "a balanced force" or "an unbalanced force".
It's a <em><u>group</u> of forces</em> that is either balanced or unbalanced.
-- The group of forces is balanced if their strengths and directions are
just right so that each force is canceled out by one or more of the others.
-- When the group of forces on an object is balanced, then the effect on the
object is just as if there were no force on it at all.
The magnetic field strength of a very long current-carrying wire is proportional to the inverse of the distance from the wire. The farther you go from the wire, the weaker the magnetic field becomes.
B ∝ 1/d
B = magnetic field strength, d = distance from wire
Calculate the scaling factor for d required to change B from 25μT to 2.8μT:
2.8μT/25μT = 1/k
k = 8.9
You must go to a distance of 8.9d to observe a magnetic field strength of 2.8μT
