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strojnjashka [21]
3 years ago
13

Magnesium is an alkaline earth metal with an atomic number of 12. It’s in the third row in the periodic table. Which expression

shows one way to find the number of valence electrons in one atom of magnesium? A. 12x3 B. 12/3 C. (12-8)-2 D. (12-2)+8 or E. (12+2)-8
Physics
2 answers:
Vikentia [17]3 years ago
7 0

Answer:

The answer is A.

Explanation: TRUST ME!

Ede4ka [16]3 years ago
6 0
The answer to your question would be A
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A small lead ball, attached to a 1.75-m rope, is being whirled in a circle that lies in the vertical plane. The ball is whirled
soldier1979 [14.2K]

Answer:

h = 57.6 m

Explanation:

First, we find the linear speed of the ball while in circular motion:

v = rω

where,

v = linear speed of ball = ?

r = radius of circle = length of rope = 1.75 m

ω = angular speed = (3 rev/s)(2π rad/1 rev) = 18.84 rad/s

Therefore,

v = (1.75 m)(18.84 rad/s)

v = 32.98 m/s

Now, we apply the 3rd equation of motion on the ball, when it breaks:

2gh = Vf² - Vi²

where,

g = - 9.8 m/s² (negative sign due to upward motion)

h = height covered = ?

Vf = Final Velocity = 0 m/s (since, the ball finally stops at highest point for a moment)

Vi = Initial Velocity = 32.98 m/s

Therefore,

2(- 9.8 m/s²)h = (0 m/s)² - (32.98 m/s)²

h = ( - 1088.12 m²/s²)/( - 19.6 m/s²)

h = 55.5 m

since, the ball was initially at a height of 2.1 m from ground. So, the total height from ground, will now become:

h = 55.5 m + 2.1 m

<u>h = 57.6 m</u>

7 0
3 years ago
Which force requires contact
jekas [21]
Gravity?????????? or maybe like any object
5 0
3 years ago
Read 2 more answers
Two parallel-plate capacitors have the same plate area, but the plate gap in capacitor 1 is twice as big as capacitor 2. If capa
-BARSIC- [3]

Answer:

Capacitance of the second capacitor = 2C

Explanation:

\texttt{Capacitance, C}=\frac{\varepsilon_0A}{d}

Where A is the area, d is the gap between plates and ε₀ is the dielectric constant.

Let C₁ be the capacitance of first capacitor with area A₁ and gap between plates d₁.

We have    

              \texttt{Capacitance, C}_1=\frac{\varepsilon_0A_1}{d_1}=C

Similarly for capacitor 2

               \texttt{Capacitance, C}_2=\frac{\varepsilon_0A_2}{d_2}=\frac{\varepsilon_0A_1}{\frac{d_1}{2}}=2\times \frac{\varepsilon_0A_1}{d_1}=2C

Capacitance of the second capacitor = 2C

6 0
3 years ago
An object is thrown directly upwards from the ground at a velocity of 9ms. Recalling that the acceleration due to gravity is −gm
olga55 [171]

Answer:

Explanation:

Given

Object is thrown with a velocity of u=9\ m/s

Acceleration due to gravity is -g (i.e. acting downward)

Vertical distance traveled by object is given by

v^2-u^2=2as  

where v=final velocity

u=initial velocity

a=acceleration

s=displacement

at maximum height final velocity is zero

0-(9)^2=2\times (-g)\times (s)

s=\frac{81}{2g}=\frac{40.5}{g}\ m

time taken to reach maximum height

using

v=u+at

0=9-gt

t=\frac{9}{g}\ s

6 0
4 years ago
The breaking car had 10,000 J of kinetic energy before breaking after breaking it had 2000 J of kinetic energy. How much thermal
WINSTONCH [101]

Answer:

8000J

Explanation:

The kinetic energy of the car lost during breaking are converted to thermal energy and are gained by the brakes.

Kinetic energy loss by car = thermal energy gained by brakes.

∆K.E = ∆T.E ....1

The Kinetic energy loss by car can be expressed as;

∆K.E = K.E1 - K.E2

Initial K.E = K.E1 = 10000J

Final K.E = K.E2 = 2000J

∆K.E= 10000J - 2000J = 8000J

From equation 1,

∆K.E = ∆T.E

∆T.E = 8,000J

thermal energy gain by brakes = 8,000J

8 0
3 years ago
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