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Juliette [100K]
3 years ago
13

There are ________ main groups in the modern periodic table of elements.

Physics
1 answer:
patriot [66]3 years ago
3 0
The Correct answer: 18

They are also known as families because they are in the same column.
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ILL GIVE BRAINLYEST
lawyer [7]

Answer:

3rd picture straight line going up right

Explanation:

3rd picture

5 0
4 years ago
Longitudinal sound waves cannot propagate through
strojnjashka [21]

Answer:

A vacuum

Explanation:

Sound waves are examples of mechanical waves. Mechanical waves are waves which are transmitted through the vibrations of the particles in a medium.

For example, sound waves in air consist of oscillations of the air particles, which vibrate back and forth (longitudinal wave) along the direction of propagation of the wave itself.

Given this definition of mechanical wave, we see that such a wave cannot propagate if there is no medium, because there are no particles that would oscillate. Therefore, among the choices given, the following one:

a vacuum

represent the only situation in which a sound wave cannot propagate through: in fact, there are no particles in a vacuum, so the oscillations cannot occur. In all other cases, instead, sound waves can propagate.

3 0
3 years ago
3) A 30 kg child slides freely across a "Slip and Slide" on LEVEL GROUND. While the child slides, the force applied to keep them
zavuch27 [327]

Answer:

a = 0.1962 m/s^2

Explanation:

The magnitude of kinetic friction exerted is given by

F_k=\mu_kN

Where, μ_k= coefficient of kinetic friction= 0.02 and N = reaction force = mg

Where m= mass = 30 Kg and, g is acceleration due to gravity =9.81 m/s^2

F_k=0.02×30×9.81 =5.886 N

Now, since, there is no applied force this kinetic friction force will cause acceleration of the child

⇒ ma = F_k

here, a is the acceleration

⇒30a = 5.886

⇒ a = 0.1962 m/s^2

4 0
3 years ago
If the energy bar was his only fuel, how far could a 68 kg person walk at 5 km/h?
goldfiish [28.3K]

An energy bar contains of 20grams of carbohydrates and 1gram is equal to 17 KJ. If the energy bar was his only fuel the total energy available is equal to (17,000 x 20) = 340,000j. Estimate KJ per hour is equal to 1539KJ, it has Time equal to (340,000/1539,000) is equal to 0.2209 hour and his Distance is equal to (5,000 x .2209) = 1.1045km. 

3 0
3 years ago
What is the source of energy for all tropical cyclones?
neonofarm [45]
The stored heat i guess..
3 0
3 years ago
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