Answer:
<em>0.25</em>
Explanation:
According to newtons law of motion
\sum F_x = ma
F_f = ma
nR = ma
nmg = ma
ng = a
n = a/g
g is the acceleration due to gravity
Given
a = 2.42m/s²
g = 9.8m/s²
Substitute into the formula;
n = 2.42/9.8
n = 0.25
<em>Hence the coefficient of kinetic friction is 0.25</em>
<em></em>
Newton's second law of motion involves the effect of force acting on a mass.
It has to be understood that this actually means the combination of any and
all individual forces acting on it, with their individual strengths and directions
all added together.
When all the individual forces acting on an object add up to zero, then the
whole group of forces is said to be 'balanced'.
When all the individual forces acting on an object don't add up to zero, then
the whole group of forces is said to be 'unbalanced'.
Notice that there's no such thing as 'a balanced force' or 'an unbalanced force'.
It's a <u>group</u> of two or more forces that's balanced or unbalanced.
Answer:
The Ptolemaic model of the universe <u><em>A) explained and predicted the motions of the planets with deferents and epicycles.</em></u>
Explanation:
Ptolemy of Alexandria built an explanation of the observed movements of the planets that remained in force for thirteen centuries. Ptolemy proposed a model of the Universe with the Earth in the center. In the model, the Earth remains stationary while the planets, the Moon and the Sun describe complicated orbits around it. In other words, Ptolemy devised a system in which he used epicycles, deferential and eccentric, and it was necessary to introduce an equating point to reproduce planetary movements. He proposed that:
a) Each planet revolves with constant velocity around a circle called an epicycle.
b) The center of the epicycle is located and moves with constant velocity around another circle called deferential.
c) The center of the deferent is located at a moving point, which travels with constant speed describing another circumference called eccentric.
d) The center of the eccentric coincides with the center of the Universe.
e) Since the Earth is not located in the center of the Universe, but very close to it, it was necessary to introduce an equating point, which is not on Earth, and from which you can see the planet move with constant speed.
However, Ptolemy put forward this geometric theory to explain mathematically the movements and failed to adjust any system of cycles, epicycles and eccentrics that accurately represented the observed movements of the planets.
Finally, <u><em>The Ptolemaic model of the universe A) explained and predicted the motions of the planets with deferents and epicycles.</em></u>
Answer:
Part a)

Part b)

Explanation:
As we know that electric force on electric charge is given as

here we have

E = 153 N/C
now force is given as

Gravitational force on electric charge near surface of earth is given as


now the ratio of two forces is given as


Part b)
Now the ball is balanced by the electric force and the force of gravity on it
so here we have



here we have

The absorption spectrum would have all the wavelengths of the light source but would have black lines where the two red and one orange lines were in the emission spectrum