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4 years ago

9

Alexandra knows that the atomic number of the element potassium, K, is 19. She also knows that one particular isotope of potassi

um has a mass number of 39. How many neutrons can be found in the nucleus of this isotope of potassium?
A) 19

B) 20

C) 39

D) 58

1 answer:

fiasKO [112]4 years ago

8 0

I believe the answer is 58 but I’m not sure

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Which kind of energy transformation occurs during skydiving? A) mechanical to gravitational B) gravitational to kinetic C) kinet

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B) gravitational to kinetic

Explanation:

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3 years ago

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The velcocity equals acceleration times time
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4 years ago

Technician A says that if starter drive clearance is too small, the starter will produce a noise during cranking. Technician B s

Ronch [10]

Answer:

Both Technicians A and B are wrong in there answers.

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3 years ago

Use the information presented in the graph to answer

Angelina_Jolie [31]

1) Segments A and C

2) Segment C

3) 40 m/s

4) 0

Explanation:

The graph is missing: find it in attachment.

1)

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$a=\frac{\Delta v}{\Delta t}$

where

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$\Delta t$ is the time interval

On a velocity-time graph, an object has acceleration if its velocity, v, changes versus time.

In this problem, we see that this situation occurs in two segments:

- In segment A, where the is a change in velocity ( $\Delta v>0$ ), so there is an acceleration

- In segment C, where the is also a change in velocity ( $\Delta v>0$ ), so there is an acceleration

B)

Here we want to find in which segment the object is slowing down.

For an object to slow down, the final velocity must be less than the initial velocity, which means that the change in velocity must be negative:

$\Delta v = v-u$

where

v is the final velocity

u is the initial velocity

For the graph in the problem, we see that:

- For segment A, the final velocity is greater than the initial velocity, so the object is speeding up

- For segment B, the final velocity is equal to the initial velocity, so the object is neither speeding up nor slowing down

- For segment C, the final velocity is less than the initial velocity, so the object is slowing down

So, the segment in which the object is slowing down is segment C.

C)

The velocity of an object is defined as the displacement covered per unit time:

$v=\frac{d}{\Delta t}$

where

d is the displacement

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On a velocity-time graph, the velocity is represented on the y-axis, while the time is represented on the x-axis.

Therefore, it is possible to read directly the value of the velocity from the y-axis.

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D)

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$a=\frac{\Delta v}{\Delta t}$

where

$\Delta v$ is the change in velocity

$\Delta t$ is the time interval

Here we want to find the acceleration for segment B. For this segment, we observe that:

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Therefore, the acceleration in segment B is:

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Answer:

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