Number of electrons in the outer energy shell
To solve the exercise it is necessary to apply the concepts related to Newton's Second Law, as well as the definition of Weight and Friction Force.
According to the problem there is a movement in the body and it is necessary to make a sum of forces on it, so that

There are two forces acting on the body, the Force that is pushing and the opposing force that is that of friction, that is

To find the required force then,

By definition we know that the friction force is equal to the multiplication between the friction coefficient and the weight, that is to say





Therefore the horizontal force applied on the block is B) 230N
Answer:
a) ΔV = 20 V
, b) Q = 35.4 10⁻⁹ C, c) C = 1.77 10⁻⁹ F
Explanation:
a) The electric potential is
ΔV = E x
ΔV = 4.0 10⁵ 50 10⁻⁶
ΔV = 20 V
c) The capacity of a capacitor is
C = ε₀ A / d
The area of a square plate is
A = L²
A = 0.10²
A = 0.01 m²
L = 50mm = 50 10⁻⁶ m
Let's calculate
C = 8.85 10⁻¹² 0.01 /50 10⁻⁶
C = 1.77 10⁻⁹ F
b) the charge is
Q = C ΔV
Q = 1.77 10⁻⁹ 20
Q = 35.4 10⁻⁹ C
After one day, the rate of increase in Delta Cephei's brightness is;0.46
We are informed that the function has been used to model the brightness of the star known as Delta Cephei at time t, where t is expressed in days;
B(t)=4.0+3.5 sin(2πt/5.4)
Simply said, in order to determine the rate of increase, we must determine the derivative of the function that provides
B'(t)=(2π/5.4)×0.35 cos(2πt/5.4)
Currently, at t = 1, we have;
B'(1)=(2π/5.4)×0.35 cos(2π*1/5.4)
Now that the angle in the bracket is expressed in radians, we can use a radians calculator to determine its cosine, giving us the following results:
B'(1)=(2π/5.4)×0.3961
B'(1)≈0.46
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Answer:
As the planets are very small and dark in comparison with stars, it makes them very hard to be found from earth.
Explanation:
Astronomy, of course, has a solution for this. As astronomers can't observe planets directly, they decided to observe the stars and search for the effects that planets have on them.
There are many ways of observing the exoplanets: Radial Velocity, Transit Photometry, Microlensing, Astrometry, Direct Imaging, etc.
Before all of this, scientist had to find ways to prove their theories. Most of their time they have spent in giving the creative answers.
Science and creativity are very much connected when we speak about the development of science. Rationality and creativity always go together.
In order to create an idea that other people will consider useful, it is important to use creativity. As no one has the exact answer when it comes to science, the adventure is to research the unknown.