D.sound insulators prevent from being transmitted better than elastic solids
Explanation:
The correct option from the given choices is that, sound insulators prevent sound from being transmitted better than elastic solids.
Sound is a form of wave that transmits energy from one point to another.
This wave form is a longitudinal wave in nature.
During the propagation of sound, it requires a material medium to move.
Sound insulators are special materials designed not to transmit sound energy.
Such materials cuts off sound. They are better than elastic solids in preventing sound transmission.
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-- Two satellites at the same distance, different masses:
The forces of gravity between two objects are directly
proportional to the product of the objects' masses. In
other words, the gravitational forces between the Earth
and an object on its surface are proportional to the mass of
the object. In other words, people with more mass weigh more
on the Earth, and the Earth weighs more on them.
If the satellites are both at the same distance from Earth,
then the Earth pulls on the one with more mass with greater
force, and also the one with more mass pulls on the Earth
with greater force.
-- Two satellites with the same mass, at different distances:
The forces of gravity between two objects are inversely
proportional to the square of the distance between them.
In other words, the gravitational
forces between the Earth
and an object are inversely proportional
to the square of
the distance between the object and the center of the Earth.
If
the satellites both have the same mass, then the Earth
pulls on the nearer one with greater force, and also the
nearer one pulls on the Earth with greater force.
-- Resistor in a circuit when the voltage changes:
The resistance depends on how the resistor was manufactured.
Its resistance is marked on it, and doesn't change. It remains
the same whether the voltage changes, the current changes,
the time of day changes, the cost of oil changes, etc.
If you increase the voltage in the circuit where that resistor is
installed, the current through the resistor increases. If the current
remains constant, then you can be sure that somebody snuck over
to your circuit when you weren't looking, and they either installed
another resistor in series with the original one to make the total
resistance bigger, or else they snipped the original one out of the
circuit and quickly connected one with more resistance in its place.
Answer:
A) magnitude = sqrrt(147.1^2 + 61^2) = 159.2 units
B)22.5° (clockwise form -ve X axis)
Explanation:
given vector = V1 = x i - 60 j
magnitude of V1 = 90
x - component can be found out by resultant formula
90^2 = x^2 + (-60)^2
x = 67.08 = 67.1 units (3sf)
FOR THE VECTOR 80 UNITS IN -VE X DIRECTION
The X component is -80-------(1)
The Y component is 0 ---------(2)
<u>For the x- component of new added vector:</u>
(1)----------- x + 67.1 = -80
x = -147.1 = -147.1
<u>For the y- component of new added vector:</u>
<u>(</u>2)---------- y - 61 = 0
y = 61.0 (3sf)
the new added vector is = -147.1 i + 61 j
magnitude = sqrrt(147.1^2 + 61^2) = 159.2 units
direction = arctan (61 / 147.1)
= 22.5° (clockwise form -ve X axis)
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