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3 years ago

Which statement correctly compares the valence electrons for atoms of francium (Fr) and barium (Ba)?

Physics

2 answers:

Sauron [17]3 years ago

8 0

Answer:

Francium has fewer valence electrons, but they are in a higher energy level

34kurt3 years ago

5 0

From the Periodic Table...

Francium is a group 1 Element and Barium is a Group 2 Element

This statement is a giveaway as it already tells you that Barium has more valence electrons than Francium since it has 2 electrons in its Outer shell.

This Eliminates Options A and B

Francium has more electrons than Barium

So It should be at a higher energy level.

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2000, the Millennium Bridge, a new footbridge over the River Thames in London, England, was opened to the public. However, after

sweet [91]

Answer:

n = 1810

A = 25 mm

Explanation:

Given:

Lateral force amplitude, F = 25 N

Frequency, f = 1 Hz

mass of the bridge, m = 2000 kg/m

Span, L = 144 m

Amplitude of the oscillation, A = 75 mm = 0.075 m

time, t = 6T

now,

Amplitude as a function of time is given as:

$A(t)=A_oe^{\frac{-bt}{2m}}$

or amplitude for unforce oscillation

$\frac{A_o}{e}=A_oe^{\frac{-b(6T)}{2m}}$

$\frac{6bt}{2m}=1$

$b=\frac{m}{3T}$

Now, provided in the question Amplitude of the driven oscillation

$A=\frac{F_{max}}{\sqrt{(k-m\omega_d^2)+(b\omega_d^2)}}$

the value of the maximum amplitude is obtained $(k=m\omega_d^2)$

thus,

$A=\frac{F_{max}}{(b\omega_d}$

Now, for n people on the bridge

Fmax = nF

thus,

max amplitude

$0.075=\frac{nF}{((\frac{m}{3T})2\pi}$

n = 1810

hence, there were 1810 people on the bridge

b) $A=\frac{F_{max}}{(b\omega_d}$

since the effect of damping in the millenium bridge is 3 times

thus,

b=3b

therefore,

$A=\frac{F_{max}}{(3b\omega_d}$

$A=\frac{1}{(3}A_o$

$A=\frac{1}{(3}0.075$

A = 0.025 m = 25 mm

6 0

3 years ago

Two hockey players , big Jim and little Tim collide head on and get tangled while going for the puck 65kg time was traveling at

12345 [234]

I will assume that big Joe is big Jim. The equation for the momentum is p=m*v, where m is the mass of the body and v is the velocity. Big Joe has a mass m=105 kg and speed v=5.2 m/s. When we input the numbers:

p=105*5.2=546 kg*(m/s).

So big Joe's momentum before the collision is p=546 kg*(m/s).

7 0

3 years ago

Calculate the power of a car that uses 12KJ of chemical energy in 6 seconds

PolarNik [594]

Explanation:

Power=work done/time

=> 12kJ/6s = 12000J/6s = 2000W = 2kW.

hope this helps you

8 0

3 years ago

Describe the conditions necessary for sublimation to occur please help

katovenus [111]

Answer:

Sublimation occurs more readily when certain weather conditions are present, such as low relative humidity and dry winds. Sublimation also occurs more at higher altitudes, where the air pressure is less than at lower altitudes. Energy, such as strong sunlight, is also needed.

6 0

3 years ago

A resistor with an unknown resistance is connected in parallel to a 13 Ω resistor. When both resistors are connected in parallel

larisa86 [58]

Answer:

R2 = 10.31Ω

Explanation:

For two resistors in parallel you have that the equivalent resistance is:

$\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}\\\\$ (1)

R1 = 13 Ω

R2 = ?

The equivalent resistance of the circuit can also be calculated by using the Ohm's law:

$I=\frac{V}{R_{eq}}\\\\R_{eq}=\frac{V}{I}$ (2)

V: emf source voltage = 23 V

I: current = 4 A

You calculate the Req by using the equation (2):

$R_{eq}=\frac{23V}{4A}=5.75\Omega$

Now, you can calculate the unknown resistor R2 by using the equation (1):

$\frac{1}{R_2}=\frac{1}{R_{eq}}-\frac{1}{R_1}\\\\R_2=\frac{R_{eq}R_1}{R_1-R_{eq}}\\\\R_2=\frac{(5.75\Omega)(13\Omega)}{13\Omega-5.75\Omega}=10.31\Omega$

hence, the resistance of the unknown resistor is 10.31Ω

8 0

3 years ago

Read 2 more answers