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nikdorinn [45]
3 years ago
14

(This is for science, not physics.)

Physics
2 answers:
Anuta_ua [19.1K]3 years ago
6 0
The answer would be B, 19 protons. Hope this helps!
Inessa [10]3 years ago
6 0
  The average mass of potassium is 39 amu and 19 electrons. 19 electrons mean there have to be 19 protons. 39-19=20. Therefore potassium has 20 neutrons. The answer is C, 20.
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With your hand parallel to the floor and your palm upright, you lower a 3-kg book downward. If the force exerted on the book by
lara31 [8.8K]

According to the net force, the acceleration of the book is 16.47 m/s².

We need to know about force to solve this problem. According to second Newton's Law, the force applied to an object will be proportional to mass and acceleration. Hence, it can be written as

∑F = m . a

where F is force, m is mass and a is acceleration

From the question above, we know that

m = 3 kg

g = 9.8 m/s²

F1 = 20 N

Find the net force

∑F = F1 + W

∑F = 20 + m . g

∑F = 20 + 3 . 9.8

∑F = 20 + 29.4

∑F = 49.4 N

Find the acceleration

∑F = m . a

49.4 = 3 . a

a = 16.47 m/s²

Find more on force at: brainly.com/question/25239010

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7 0
1 year ago
57.9 g of gold has a volume of 3 cm³ what is the density of gold in g/ centimeters cubed
Grace [21]
D=m÷v

so density would be 57.9 ÷ 3 = 19.3 g/cm³
7 0
3 years ago
Read 2 more answers
An object of mass, m1 with a velocity, v1 collides with another object at rest (v2 = 0) with a mass, m2. After the collision, m1
goblinko [34]

Answer:

v"_{1} = v_{1} tanΘ

v^{"} _{2} = \frac{m_{1}v_{1}}{m_{2}cos}Θ

Θ = tan^{-1}(\frac{v^{"} _{1} }{v_{1} } )

Explanation:

Applying the law of conservation of momentum, we have:

Δp_{x = 0}

p_{x} = p"_{x}

m_{1}v_{1} = m_{2}v"_{2} cosΘ (Equation 1)

Δp_{y} = 0

p_{y} = p"_{y}

0 = m_{1} v"_{1} - m_{2} v"_{2} sinΘ (Equation 2)

From Equation 1:

v"_{2} = \frac{m_{1}v_{1}}{m_{2}cos}Θ

From Equation 2:

m_{2} v"_{2}sinΘ = m_{1} v_{1}

v"_{1} = \frac{m_{2} v"_{2}sinΘ}{m_{1} }

Replacing Equation 3 in Equation 4:

v"_{1}=\frac{m_{2}\frac{m_{1}v_{1}}{m_{2}cosΘ}sinΘ}{m_{1}}

v"_{1}=v_{1}\frac{sinΘ}{cosΘ}

v"_{1}=v_{1}tanΘ (Equation 5)

And we found Θ from the Equation 5:

tanΘ=\frac{v"_{1}}{v_{1}}

Θ=tan^{-1}(\frac{v"_{1}}{v_{1}})

7 0
3 years ago
We reduce friction in machines? why<br>​
kvv77 [185]

Answer:

friction reduces the efficiency of machines, thus we must reduce the friction force that is acting upon it.

5 0
3 years ago
Read 2 more answers
Choose all the answers that apply. The continents _____. were once connected have always been in the same location are slowly dr
svetoff [14.1K]

Answer: the correct options are

- were once connected

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- Asia, Africa, Europe, Australia, North America, South America, and Antarctica.

These continents were once connected forming a supercontinent called PANGAEA

during the late palaeozoic and early mesozoic eras, millions of years ago.

Alfred Wegener, who is a German meteorologist, in 1912 came up with a hypothesis that the continents are slowly drifting the earth. He called the movement continental drift.

The continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. In recent studies, through the science of plate tectonics, we where able to understand the mechanism through which continental drift occurs. The mechanism includes:

- processes of seafloor spreading,

- rift valley formation, and

- subduction (where heavier tectonic plates sink beneath lighter ones).

7 0
3 years ago
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