Answer:
4.35×10⁻⁴ m
Explanation:
(a)
From wave,
v = λf...................... Equation 1
Where v = speed of sound in air, λ = wavelength of sound, f = frequency of sound.
Make λ the subject of formula in equation 1
λ = v/f................. Equation 2
Given: v = 343, f = 3.45 MHz = 3.45×10⁶ Hz
Substitute into equation 2
λ = 343/(3.45×10⁶)
λ = 99.42×10⁻⁶ m
λ = 9.942×10⁻⁵ m
(b)
using,
v' = λ'f............... Equation 3
Where v' = speed of sound in tissue, λ' = wavelength of sound in tissue.
make λ' the subject of the equation
λ' = v'/f......................Equation 4
Given: v' = 1500 m/s, f = 3.45 MHz = 3.45×10⁶ Hz
Substitute into equation 4
λ' = 1500/(3.45×10⁶)
λ' = 434.783×10⁻⁶
λ' ≈ 4.35×10⁻⁴ m.
1) The charge left on the fur is equal and opposite to the charge transferred to the rod:
In fact, when the rod is rubbed with the fur, a net charge of
has been transferred to the rod, leaving it negatively charged. If we assume the fur was initially neutral, this means that we have now an excess of positive charges on the fur, and the amount of this charge must be equal (in magnitude, but with opposite sign) to the charge transferred to the rod.
2) The mass transferred to the rod is equal to the total mass of the electrons transferred to the rod.
The charge transferred to the rod is
The charge of 1 electron is
So the number of electrons transferred is
The mass of 1 electron is
, therefore the total mass transferred to the rod is
The goal of scientific method is to produce public knowledge. That is knowledge available to any person with sufficient education, all such knowledge can be verified by or deduced from experiments and observations.
Answer:
The objects can be distinguished by their weight instead of by mass.
Explanation
Because mass is constant, the two objects cannot be distinguished by mass.
However, gravitational acceleration varies in outer space. Therefore the heavier mass will register a higher reading on a weighing scale.
Note that an object of mass M weighs Mg, where g = acceleration due to gravity.
Answer:
Option D
When the Moon is at right angles to the direction of the Sun.
Explanation:
The moon does not shine on its own, for example, like the sun that emits light as a consequence of its temperature. Instead, the moon is reflecting the sunlight (that is known as albedo).
The moon orbits the earth in a time 27.3 day, a sidereal period. According to that and the fact the Earth orbits the Sun, the moon will show different phases when is reflecting the sunlight along a month due to the configuration of those three celestial objects (Moon, Earth and the Sun).
When there is a Right angle between the Moon and to the direction of the Sun, half its face will appear to be illuminated in the night sky (that is called First Quarter).
Notice that when the Moon is between the Earth and the Sun it will be illuminated in its back, so it is not possible to see it from the Earth (that is called new moon).
However, a solar eclipse doesn't happens every month since the orbital plane of the moon is not in the same plane as the Earth's orbital plane with respect to the Sun.
