Help!! If an atom has 7 protons and 8 neutrons, and is not in an excited state, how many electrons would Bohr say the atom has?

2. Two projectiles thrown from the same point at angles 0,=60° and 02=30° with the horizontal,

Liono4ka [1.6K]

Answer:

The answer is below

Explanation:

The maximum height (h) of a projectile with an initial velocity of u, acceleration due to gravity g and at an angle θ with the horizontal is given as:

$h=\frac{u^2sin^2\theta}{2g}$

Given that the two projectile has the same height.

$For\ the\ first\ projectile\ with\ an\ angle\ \60^0 \ with\ the\ horizontal\ and initial\ velocity\ u_1:\\\\h=\frac{u_1^2sin^260}{2g} =\frac{0.75u_1^2}{2g} \\\\For\ the\ second\ projectile\ with\ an\ angle\ \30 \ with\ the\ horizontal\ and initial\ velocity\ u_2:\\\\h=\frac{u_2^2sin^230}{2g} =\frac{0.25u_2^2}{2g}\\\\\frac{0.25u_2^2}{2g}=\frac{0.75u_1^2}{2g}\\\\0.25u_2^2=0.75u_1^2\\\\\frac{u_1^2}{u_2^2} =\frac{0.25}{0.75} \\\\\frac{u_1^2}{u_2^2}=\frac{1}{3} \\$ $\\\frac{u_1}{u_2}=\sqrt\frac{1}{3}$

8 0

3 years ago

Light traveling from water to a gemstone strikes the surface at an angle of 80.0º and has an angle of refraction of 15.2º . (a)

7nadin3 [17]

Answer:

a

The the speed of light in the gemstone is $v= 0.599*10^8 m/s$

b

The unreasonable thing about this is that the speed of ligth in the gemstone is too low

the speed is 19% of the speed of light which is very low

c

One main unreasonable or inconsistent factor is that the assumption that the differnce between the angle of incidence and angle of refraction is very large

Explanation:

From the question we are told that

The angle of incidence $i = 80^o$

The angle of refraction $r = 15.2^o$

From Snell's law we have ,

$n_1 sin \theta_1 = n_2 sin \theta_2$

Where $n_1$ is the refractive index of the first medium (water) with a constant value of $n_1 = 1..333$

$n_2$ is the refractive index of the second medium (gem stone)

$\theta_1$ is the angle between the beam and perpendicular surface of the first medium

$\theta_2$ is the angle between the beam an the perpendicular surface of the second medium

Making the $n_2$ the subject of the formula

$n_2 = n_1 \frac{sin \theta_1}{sin \theta_2}$

$= (1.333)(\frac{sin (80.0)}{sin 15.2} )$

$= 5.007$

Generally refractive index of a material is mathematically represented

$n = \frac{c}{v}$

Where c is the speed light

v is the speed of light observed in a medium

Making v the subject

$v = \frac{c}{n}$

substituting value for gem stone

$v = \frac{3.0*10^8}{5.007}$

$v= 0.599*10^8 m/s$

7 0

3 years ago

Define resistance and describe what would happen to a light bulb if the voltage increased but the resistance stayed the same. Re

Anarel [89]

Answer:

The light bulb would glow brighter.

Explanation:

Resistance is the opposition to current flow and in Ohm's law is represented as a constant in the equation V = IR with V the voltage, I the current and R the resistance.

Now let's assume we are in a series circuit that has only one path for electricity to follow to better explain what would happen to a light bulb if the voltage increased but the resistance stayed the same. Based on ohm's law equation, the voltage is directly proportional to the current and the resistance is constant. An increase in the voltage is therefore an increase in the current which flows throught the light bulb making it glow brighter while a decrease in voltage results in a decrease in current flowing through the light bulb making it dim.

8 0

3 years ago

Given the thermochemical equations X2+3Y2⟶2XY3ΔH1=−370 kJ X2+2Z2⟶2XZ2ΔH2=−120 kJ 2Y2+Z2⟶2Y2ZΔH3=−270 kJ Calculate the change in

Alchen [17]

Answer : The change in enthalpy of the reaction is, -310 kJ

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The given main reaction is,

$4XY_3+7Z_2\rightarrow 6Y_2Z+4XZ_2$ $\Delta H=?$