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Flura [38]
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
Physics
1 answer:
fiasKO [112]4 years ago
8 0
I believe the answer is 58 but I’m not sure
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Some birds migrate 20,000 miles. If 1 mile equals 1.6 kilometers, calculate the distance these birds fly in kilometers.
faust18 [17]
Set up a proportion

1 mile/1.6 km = 20,000miles/x

Cross Multiply
x = (20,000) * (1.6)
x = 32,000 kilometers
6 0
4 years ago
Read 2 more answers
What will be the ME of a machine that produces a 240 N work with a 300
Elden [556K]

Answer:

Efficiency = 80%

Explanation:

Given the following data;

Work output = 240 N

Work Input = 300 N

To find the mechanical efficiency of a machine;

Efficiency = \frac {Out-put \; work}{In-put \; work} * 100

Substituting into the equation, we have;

Efficiency = \frac {240}{300} * 100

Efficiency = 0.8 * 100

Efficiency = 80%

Therefore, the mechanical efficiency of the machine is 80 percent.

3 0
3 years ago
I need help understanding this concept . Would appreciate it so much. Thank you
Firlakuza [10]

Answer:

Explanation:

Both these questions are based on the Universal Law of Gravitation, which is given by :

F = Gm1m2 / r²

2) F = 6.67 x 10⁻¹¹ x 8 x 10³ x 1.5 x 10³ / 1.5 x 1.5

   F = 6.67 x 10⁻⁵ x 8 / 1.5

   F = 35.57 x 10⁻⁵ N

3) F = 6.67 x 10⁻¹¹ x 7.5 x 10⁵ x 9.2 x 10⁷ / 7.29 x 10⁴

   F = 6.67 x 10⁻³ x 7.5 x 9.2 / 7.29

   F = 63.13 x 10⁻³ N

7 0
3 years ago
A pharmacist attempts to weigh 100 milligrams of codeine sulfate on a balance with a sensitivity requirement of 4 milligrams. Ca
ira [324]

Answer:

4 %

2 ) 3.42 %

Explanation:

Sensitivity requirement of 4 milligram means it is not sensitive below 4 milligram or can not measure below 4 milligram .

Given , 4 milligram is the maximum error possible .

Measured weight = 100 milligram

So percentage maximum potential error

= (4 / 100)  x 100

4 %

2 )

As per measurement

weight of 6 milliliters of water

= 48.540 - 42.745 = 5.795 gram

6 milliliters of water should measure 6 grams

Deviation = 6 - 5.795 = - 0.205 gram.

Percentage of error =(.205 / 6 )x 100

= 3.42 %

3 0
3 years ago
The 0.01 kg marble is dropped from rest at A through the smooth glass tube and accumulate in the basket at C as shown in Figure
Anuta_ua [19.1K]

Crazy Wally Ok Ok ok hhahahaha

4 0
3 years ago
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