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Gnesinka [82]
3 years ago
11

The discovery of what element showed the usefulness of Mendeleev’s periodic table?

Physics
2 answers:
lesya [120]3 years ago
7 0
A. Gallium

'cause he predicted it's physical properties before it's discovery! After that, it was proved that Mendeleev's periodic table was useful.

Hope this helps!
jekas [21]3 years ago
4 0
<h3><u>Answer;</u></h3>

A. Gallium

<h3><u>Explanation;</u></h3>
  • Mendeleev arranged the elements in rows in order of increasing mass so that elements with similar properties were in the same column.
  • <em><u>The discovery of new elements such as gallium demonstrated the usefulness of Mendeleev’s table because the close match between Mendeleev’s predictions and the actual properties of new elements showed how useful his periodic table could be. </u></em>
  • Mendeleev’s efforts more successful because he provided an organizing principle that worked for all off the known elements.


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The patellar tendon attaches to the tibia at a 20 deg angle 3 cm from the axis of rotation at the knee. If the force generated i
gregori [183]

Answer:

the resulting angular acceleration is 15.65 rad/s²

Explanation:

Given the data in the question;

force generated in the patellar tendon F = 400 N

patellar tendon attaches to the tibia at a 20° angle 3 cm( 0.03 m ) from the axis of rotation at the knee.

so Torque produced by the knee will be;

T = F × d⊥

T = 400 N × 0.03 m × sin( 20° )

T = 400 N × 0.03 m × 0.342

T = 4.104 N.m

Now, we determine the moment of inertia of the knee

I = mk²

given that; the lower leg and foot have a combined mass of 4.2kg and a given radius of gyration of 25 cm ( 0.25 m )

we substitute

I = 4.2 kg × ( 0.25 m )²

I = 4.2 kg × 0.0626 m²

I = 0.2625 kg.m²

So from the relation of Moment of inertia, Torque and angular acceleration;

T = I∝

we make angular acceleration ∝, subject of the formula

∝ = T / I

we substitute

∝ = 4.104 / 0.2625

∝ = 15.65 rad/s²

Therefore, the resulting angular acceleration is 15.65 rad/s²

8 0
3 years ago
To reduce inductive reactance, what devices are normally placed on transmission or distribution lines?
UkoKoshka [18]

Answer : Capacitors

Explanation : Capacitors are normally  placed on transmission or distribution lines when to reduce inductive reactance.

This is because it enhances electromechanical and voltage stability , limit voltage dips at network nodes and reduces the power loss.

So, we can say that inductive reactance normally replace by the capacitors.



4 0
2 years ago
What is an unbalanced force
Butoxors [25]
There's no such thing as "an unbalanced force".

If all of the forces acting on an object all add up to zero, then we say that
<span>the group </span>of forces is balanced.  When that happens, the group of forces
has the same effect on the object as if there were no forces on it at all. 

An example: 
Two people with exactly equal strength are having a tug-of-war.  They pull
with equal force in opposite directions.  Each person is sweating and straining,
grunting and groaning, and exerting tremendous force.  But their forces add up
to zero, and the rope goes nowhere.  The <u>group</u> of forces on the rope is balanced.

On the other hand, if one of the offensive linemen is pulling on one end of
the rope, and one of the cheerleaders is pulling on the other end, then their
forces don't add up to zero, because even though they're opposite, they're
not equal.  The <u>group</u> of forces is <u>unbalanced</u>, and the rope moves.

A group of forces is either balanced or unbalanced.  A single force isn't.
7 0
3 years ago
What is demonstrated by water moving up a straw?
Alja [10]
<span>The answer is C: water is drawn up a straw by cohesion and adhesion. Water molecules stick to one another and the walls of the straw, just like in a capillary.
Cohesion is the attractive force between like materials (between water
molecules).
Adhesion is the attractive force between twounlike materials (such as between
water and a solid container).
Capillary action is the tendency of a liquid to rise innarrow tubes or small openings as a result of adhesion and cohesion.
The liquid water molecules bind to the straw—a process known as adhesion.  In the narrow space of the straw, the interaction of cohesion and adhesion causes theliquid to be drawn upward in the straw.</span>
8 0
3 years ago
Read 2 more answers
A spool of thread has an average radius of 1.00 cm. If the spool contains 62.8 m of thread, how many turns of thread are on the
Simora [160]

To solve this problem we will start from the given concept in which the number of turns is equivalent to the length of the thread per circumference of spool. That is:

N = \frac{l}{\phi}

Where,

l = length of the thread

\phi= circumference of spool

For \phi we have that,

\phi = 2\pi r \rightarrow 2\pi (0.01)

For l  we have that

l = 62.8m

Finally the number of Turns would be,

N = \frac{l}{\phi}

N = \frac{62.8}{2\pi (0.01)}

N = 1000turns

Therefore the number of turns of thread on the spool are 1000turns.

7 0
3 years ago
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