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-Dominant- [34]
3 years ago
7

Alaina is pregnant and has undergone prenatal testing. The initial tests raised some red flags, and a subsequent DNA test confir

med that the fetus does in fact have three copies of chromosome 21, or:
Down syndrome.
Physics
1 answer:
vova2212 [387]3 years ago
3 0

Answer:zsg

Explanation:gzdbzd

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An atom with the expected number of neutrons, protons, and electrons is called a(n)
ryzh [129]

Answer:

Stable atom

Explanation:

A stable atom is one that has a balanced nuclear inter-particle force reaction as such the binding energy of a stable atom is sufficient to permanently keep the nucleus as one unit. Examples of a stable atom are the atoms of  monoisotopic elements such as fluorine, sodium, iodine, gold, aluminium, and cobalt.

In a stable atom the expected number of proton, neutron, and electron are present while in an unstable atom or radioactive atom, there are more than the expected number of neutrons or protons, such that the internal energy of the nucleus is excessive and more than the binding energy, which can lead to radioactive decay.

6 0
3 years ago
A stone is thrown vertically upward with a speed of 15.5 m/s from the edge of a cliff 75.0 m high .
rjkz [21]

a) 2.64 s

We can solve this part of the problem by using the following SUVAT equation:

s=ut+\frac{1}{2}at^2

where

s is the displacement of the stone

u is the initial velocity

t is the time

a is the acceleration

We must be careful to the signs of s, u and a. Taking upward as positive direction, we have:

- s (displacement) negative, since it is downward: so s = -75.0 m

- u (initial velocity) positive, since it is upward: +15.5 m/s

- a (acceleration) negative, since it is downward: so a= g = -9.8 m/s^2 (acceleration of gravity)

Substituting into the equation,

-75.0 = 15.5 t -4.9t^2\\4.9t^2-15.5t-75.0 = 0

Solving the equation, we have two solutions: t = -5.80 s and t = 2.84 s. Since the negative solution has no physical meaning, the stone reaches the bottom of the cliff 2.64 s later.

b) 10.4 m/s

The speed of the stone when it reaches the bottom of the cliff can be calculated by using the equation:

v=u+at

where again, we must be careful to the signs of the various quantities:

- u (initial velocity) positive, since it is upward: +15.5 m/s

- a (acceleration) negative, since it is downward: so a = g = -9.8 m/s^2

Substituting t = 2.64 s, we find the final velocity of the stone:

v = 15.5 +(-9.8)(2.64)=-10.4 m/s

where the negative sign means that the velocity is downward: so the speed is 10.4 m/s.

c) 4.11 s

In this case, we can use again the equation:

s=ut+\frac{1}{2}at^2

where

s is the displacement of the package

u is the initial velocity

t is the time

a is the acceleration

We have:

s = -105 m (vertical displacement of the package, downward so negative)

u = +5.40 m/s (initial velocity of the package, which is the same as the helicopter, upward so positive)

a = g = -9.8 m/s^2

Substituting into the equation,

-105 = 5.40 t -4.9t^2\\4.9t^2 -5.40 t-105=0

Which gives two solutions: t = -5.21 s and t = 4.11 s. Again, we discard the first solution since it is negative, so the package reaches the ground after

t = 4.11 seconds.

5 0
3 years ago
Read 2 more answers
Why is it important foe scientists to know how many valence electrons a given element has
Vikentia [17]
Because the number of valence electrons of an element determines the properties and in particular the reactivity of that element.

In fact, elements of the first group (i.e. only one valence electron) have high reactivity, because they can easily give away their valence electron to atoms of other elements forming bonds. On the contrary, elements of the 8th group (noble gases) have their outermost shell completely filled with electrons, so they do not have valence electrons, and they have little or no reactivity at all.
3 0
3 years ago
Two masses are attracted by a gravitational force of 7 N.
damaskus [11]

Answer:

The answer to your question is: F  = 0.4375 N. The force will be 16 times lower than with the first conditions.

Explanation:

Data

F = 7 N

F = ?  if the masses is quartered

Formula

F = \frac{Km1m2}{r2}

Process

Normal conditions F = Km₁m₂/r²  = 7              

When masses quartered        F = K(m₁/4)(m₂/4)/r²  = ?

                                                F = K(m₁m₂/16)/r²

                                                F = K(m₁m₂/16r²      = 7/16  = 0.4375 N

3 0
3 years ago
Define the term work​
bagirrra123 [75]

Answer:

Work, in physics, measure of energy transfer that occurs when an object is moved over a distance by an external force

Explanation:

at least part of which is applied in the direction of the displacement. ... To express this concept mathematically, the work W is equal to the force f times the distance d, or W = fd.

5 0
3 years ago
Read 2 more answers
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