Answer:
15 N and 3.061
Explanation:
From the question,
The minimum force of friction to keep the book from sliding = 15 N.
using
F = mgμ................. Equation 1
Where F = Frictional Force, m = mass of the book, g = acceleration due to gravity, μ = coefficient of friction.
make μ the subject of the equation
μ = F/mg............... Equation 2
Given: F = 15 N, m = 0.5 kg, g = 9.8 m/s²
Substitute into equation 2
μ = 15(0.5×9.8)
μ = 15/4.9
μ = 3.061
Hence the coefficient of friction to keep the book from sliding = 3.061
The andromeda galaxy is approaching our galaxy with a radial velocity of 120 km/s. given the galaxies present separation of 800 kpc, and neglecting both the transverse component of the velocity and the effect of gravity in accelerating the motion, estimate when the two galaxies will collide.
The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy that is 2.5 million light-years away from Earth and the closest big galaxy to the Milky Way. It has a diameter of roughly 46.56 kiloparsecs.
The Milky Way, which houses the Solar System and Earth, and the Andromeda Galaxy are anticipated to collide in roughly 4.5 billion years. This galactic collision will take place between the two largest galaxies in the Local Group. The Andromeda galaxy is the brightest galaxy outside of our solar system. It is the furthest object that the majority of us humans can see with our unaided eyes at a distance of 2.5 million light-years.
To learn more about Andromeda galaxy please visit-
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Answer:
Explanation:
The electrostatic attraction between the nucleus and the electron is given by:
(1)
where
k is the Coulomb's constant
Ze is the charge of the nucleus
e is the charge of the electron
r is the distance between the electron and the nucleus
This electrostatic attraction provides the centripetal force that keeps the electron in circular motion, which is given by:
(2)
where
m is the mass of the electron
v is the speed of the electron
Combining the two equations (1) and (2), we find
And solving for v, we find an expression for the speed of the electron:
