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3 years ago

The rounded atomic mass of K is _____ K stands for _ and has ___ valence electron(s).

Physics

2 answers:

Free_Kalibri [48]3 years ago

8 0

Answer:

The rounded atomic mass of K is

K stands for

Potassium

and has

valence electron(s).

netineya [11]3 years ago

4 0

Answer:

Potassium

k = Potassium

Potassium Has 19 Electrons

the atomic mass is 39.0983

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A pendulum consists of a 1.5 kg stone swinging on a 4.3 m string of negligible mass. The stone has a speed of 8.4 m/s when it pa

Ad libitum [116K]

Answer:

(a) v = 1.54m/s, (b) Θ = 80.6° and (c) E = 52.92J

Explanation:

(a) At the lowest point, the total energy is giving by:

$E_{T}_{0} = E_{K}_{0} + E_{P}_{0} = \frac {1}{2} mv_{0}^{2} + mgy_{0}$

where, $E_{K}$ : kinetic energy, $E_{P}$ : potential energy, m: pendulum's mass, v: speed of the pendulum, g:gravity and y: heigh of the pendulum.

$E_{T}_{0} = \frac {1}{2} mv_{0}^{2} + mg(0) = \frac {1}{2} (1.5)(8.4)^{2} = 52.92 J$ (1)

When the string is at 64° from the vertical, the total energy is:

$E_{T}_{f} = \frac {1}{2} mv_{f}^{2} + mgy_{f}$ (2)

At this point, $y_{f}$ is:

$y_{f} = L - Lcos(\Theta)$ (3)

where L: longitude of the pendulum

$y_{f} = 4.3 m (1 -cos(64)) = 2.42 m$

By conservation of energy, we can calculate the speed of the string, at 64 ° to the vertical. Equaling equations (1) and (2):

$E_{T}_{0} = E_{T}_{f} = \frac {1}{2} mv_{f}^{2} + mgy_{f}$

$v_{f} = \sqrt \frac{2(E_{T}_{0} - mgy_{f})}{mg}}$

$v_{f} = \sqrt \frac{2(52.92 - 1.5 \cdot 9.8 \cdot 2.42)}{1.5 \cdot 9.8}} = 1.54 \frac{m}{s}$

(b) Smilarly, by conservation of energy we can find the greatest angle, assuming that vf = 0 at the greatest angle reached:

$\frac {1}{2} mv_{0}^{2} + mgy_{0} = \frac {1}{2} mv_{f}^{2} + mgy_{f}$

$y_{f} = \frac {E_{0}}{mg} = \frac {52.92}{(1.5)(9.8)} = 3.6 m$

Using the heigh calculated in equation (3) we can find the angle:

$\Theta = Arccos (\frac {L - y_{f}}{L}) = Arccos (\frac {4.3 - 3.6}{4.3}) = 80.6^\circ$

(c) The total mechanical energy at the lowest point is giving by:

$E_{T} = E_{K} + E_{P} = \frac {1}{2} mv_{0}^{2} + 0 = \frac {1}{2} (1.5)(8.4)^{2} = 52.92 J$

Have a nice day!

8 0

3 years ago

Your cell phone typically consumes about 300 mW of power when you text a friend. If the phone is operated using a lithium-ion ba

hichkok12 [17]

Answer:

I = 0.0857 A

Explanation:

Given that,

Power consumed by the cellphone, P = 300 mW

The voltage of the battery, V = 3.5 V

Let I is the current flowing through the cell-phone. We know that,

P = VI

Where

I is the current

So,

$I=\dfrac{P}{V}\\\\I=\dfrac{300\times 10^{-3}}{3.5}\\\\I=0.0857\ A$

So, the current flowing the cell-phone is 0.0857 A.

4 0

3 years ago

If the _ of the proteins changes, this is called a mutation

Delicious77 [7]

Answer:

If the DNA of the proteins changes, this is called a mutation.

Explanation: Hope it helps you :))))

Have a good day

6 0

2 years ago

A boat has a mass of 6800 kg. Its engines generate a drive force of 4100 N due west, while the wind exerts a force of 800 N due

mezya [45]

Answer:

The boat's acceleration are: a= 0.3 m/s² in west direction.

Explanation:

Fm= 4100 N

Fwi= 800 N

Fwa= 1200 N

Fm - Fwi - Fwa= m *a

clearing a:

a= 0.3 m/s²

8 0

4 years ago

Calculate the work done in moving a charge of 2 coulombs across 2 points having a potential difference of 12 volts

Veseljchak [2.6K]

Answer:

Work is done in moving a charge of 2 coulomb across two points having a potential difference of 12 volt is 24 joule .

Explanation:

8 0

3 years ago

The rounded atomic mass of K is _______ K stands for _____ and has _____ valence electron(s).

The rounded atomic mass of K is _____ K stands for _ and has ___ valence electron(s).