Which type of electromagnetic radiation is useful in communications
technology?

Answer:

Time, t = 0.439 seconds

Explanation:

Given the following data;

Angle, x = 21°

Initial velocity, u = usinx = 12Sin21° = 4.3004m/s

We know that acceleration due to gravity is equal to 9.8m/s

Final velocity = 0m/s since it reached its highest trajectory.

To find the time, we would use the first equation of motion;

V = U + gt

0 = 4.3004 + (-9.8)t

0 = 4.3004 - 9.8t

9.8t = 4.3004

t = 4.3004/9.8

t = 0.439 seconds

Therefore, it will take the ball 0.439 seconds to reach the top of its trajectory.

Answer: 0.44 s

Explanation:

that’s what I got correct on my test in physics ;)

Answer:

Answer is explained in the explanation section below.

Explanation:

Note: This question is incomplete and lacks the necessary diagram of the circuits to solve for this question. However, I have found similar question on the internet and dragged the diagrams out of it. I have attached the diagrams of the circuits for your ease. It has two circuits to be solved. Attachment 1 refers to first circuit and Attachment 2 refers to second circuit.

Solution:

We are asked to find the potential difference and current through each resistor.

So,

Calculations for Circuit 1: Please refer to Attachment 1

First we need to find the Resistance:

Req = [tex]\frac{9 . 6}{9+6} +3[/tex]

R = 6.6 Ohm

Now, we know that:

V = IR

So,

I = V/R

V = 12 V

I = 12 V/ 6.6 ohm

I = 1.82 Amperes.

Now,

The Potential Difference through 3 ohm resistor:

P.D = [tex]V_{3}[/tex] = 1.82 x 3

[tex]V_{3}[/tex] = 5.45 V

Now,

The Potential Difference through 6 ohm and 9 ohm resistor:

[tex]V_{6/9}[/tex] =  12V - 5.45V

[tex]V_{6/9}[/tex] =  6.545V

Now,

The current through 6 ohm is:

[tex]I_{6}[/tex] = [tex]\frac{6.545}{6}[/tex]

[tex]I_{6}[/tex] = 1.09 A

Now,

The Current through 9 ohm is:

[tex]I_{9}[/tex]  = [tex]\frac{6.545}{9}[/tex]

[tex]I_{9}[/tex]  = 0.72 A

Similarly,

Calculations for Circuit 2: Please refer to attachment 2:

Req = [tex]\frac{(30+50).90}{90+(30+50)} +20[/tex]

Req = 62.35 ohm

I = V/R

I = 12 V/ 62.35ohm

I = 0.192 Amperes.

Now,

The The Potential Difference through 20 ohm resistor:

[tex]V_{20}[/tex] = 20 x 0.192

[tex]V_{20}[/tex] = 3.849 V

Now,

The The Potential Difference through 90 ohm resistor:

[tex]V_{90/(30+50)}[/tex] = 12 - 3.849

[tex]V_{90/(30+50)}[/tex] = 8.150

Now,

The Current through 90 ohm is:

[tex]I_{90}[/tex]  = 8.1509/90

[tex]I_{90}[/tex] = 0.0905 Amperes

Now,

The Current through 30 and 50 ohm is:

[tex]I_{30/50}[/tex] = 0.192 - 0.0905

[tex]I_{30/50}[/tex]  = 0.101 A

Now,

The Potential Difference through 50 ohm resistor:

[tex]V_{50}[/tex] = 50 x 0.101

[tex]V_{50}[/tex]  = 5.094 V

The Potential Difference through 30 ohm resistor:    

[tex]V_{30}[/tex] = 30 x  0.101

[tex]V_{30}[/tex] = 3.0566 V

professional is the answer

3rd

Answer:

the magnitude of the constant acceleration is 6.98 m/s²

Explanation:

Given;

distance traveled at a constant velocity, d = 130 m

time of motion, t = 4.9 s

The constant velocity is calculated as;

[tex]v = \frac{d}{t} \\\\v = \frac{130}{4.9} \\\\v = 26.53 \ m/s[/tex]

The car comes to a stop in 3.8 s.

When the car comes to a complete stop, the final velocity of the car will be zero.

the constant acceleration is calculated as;

v = u + at

0 = u + at

at = -u

a = -u/t

a = (-26.53) / (3.8)

a = -6.98 m/s²

Therefore, the magnitude of the constant acceleration is 6.98 m/s²

Answer:

Oppressors have a repressive attitude toward others. They have a need for power and dominance.

Explanation:

Oppression is the painful experience of deliberate arbitrariness, violence and abuse of power inflicted on an individual, society or group of people. The term repression is often used synonymously for this.  

Oppression arises from the general, also unconscious, assumption that a certain group of people is inferior or without rights. Oppression is seldom limited to governmental activities. Individuals can also be victims of oppression if they lack the solidarity of a social group.

Oppressive individuals, in turn, are those who exert repression on others. They are generally narcissistic and megalomaniacal people, who have a wrong self-perception of their virtues and negatively weigh the virtues of other people.

Answer:

the heat emitted by potatoes is much less than the heat emitted by turkey

Explanation:

The heat transfer is given by

        Q = m [tex]c_{e}[/tex] ΔT

where m is the mass of the body, c_e is the specific heat and ΔT is the change in temperature of the body

in this case they ask us to appear the heat emitted by the potatoes and the turkey.

From the tables found the specious colors of both

potato     c_e = 0.82 Kcal / kg ºC

turkey      c_e = 0.72 Kcal / kg ºC

Since the two bodies have the same initial temperature and we assume that they reach the same final (ambient) temperature, the ratio of the heat emitted is

          Q₁ / Q₂ =  [tex]\frac{ m_1 \ c_{e1} }{m_2 \ c_{e2} }[/tex]

where we use the rise 1 for the potatoes and the su index 2 for the turkey

the mass of the potatoes can be estimated at approximately m = 1 ka

we substitute

          Q₁ / Q₂ =  [tex]\frac{1 \ 0.82}{ 20 0.72}[/tex]

           Q₁ /Q₂ = 0.0569

           Q₁ = 0.0569 Q₂

therefore the heat emitted by potatoes is much less than the heat emitted by turkey

Answer:

[tex]F_4=\frac{4}{b}F_1[/tex]

Explanation:

Centripetal force is the net force acting on a body which makes it move along a curved path. This force is always towards the center of curvature.

The centripetal force is given by:

F = mv² / r

where m is the mass of the body, v is the velocity of the body, r is the radius, F is the centripetal force and v²/r is the centripetal acceleration.

Given that:

[tex]\frac{v_4}{v_1}=2\\\\v_4=2v_1\\\\ Also, radius\ of\ lane\ 4(r_4)=2*radius\ of\ lane\ 1\\\\Let\ r_1\ be\ radius\ of\ lane\ 1,m=mass\ of\ runner\ in\ lane\ 1=mass\ of\ runner\ in\ lane\ 4\ \\and\ v_4=velocity\ of\ runner\ in\ lane\ 4.\ Hence:\\\\r_4=b*r_1=br_1\\\\The\ centripetal\ force\ for\ lane\ 4(F_4)\ is:\\\\F_4=\frac{mv_4^2}{r_4}\\\\ F_4=\frac{m(2v_1)^2}{br_1}\\\\F_4= \frac{4mv_1^2}{br_1} \\\\But\ F_1=\frac{mv_1^2}{r_1}\\\\Hence\ F_4=\frac{4}{b}F_1[/tex]

F4 is equal to 4/b F1. A further explanation is provided below.

According to the question,

The net force of the object in uniform circular motion will be:

→ [tex]F = \frac{mv^2}{r}[/tex]

∴ [tex]F_1 = \frac{m_1 v_1^2}{r_1}[/tex]

  [tex]F_4 = \frac{m_4 v_4^2}{r_4}[/tex]

Now,

→ [tex]\frac{F_1}{F_4} = \frac{m_1}{m_4}\times (\frac{v_1}{v_4} )^2\times \frac{r_4}{r_1}[/tex]

   [tex]\frac{F_1}{F_4} = \frac{1}{4}\times b[/tex]

   [tex]F_1 = \frac{b}{4} F_4[/tex]

   [tex]F_4 = \frac{4}{b} F_1[/tex]

Thus the above response i.e., "option b" is correct.

Learn more:

https://brainly.com/question/4527006

Answer:

Option B. 28 N

Explanation:

From the question given above, the following data were obtained:

Coefficient of static friction (μ) = 0.35

Normal force (N) = 80 N

Frictional force (F) =?

The coefficient of static friction, frictional force and the normal force are related according to the following equation:

Coefficient of friction = frictional force / normal force

μ = F/N

With the above formula, we can obtain the frictional force as follow:

Coefficient of static friction (μ) = 0.35

Normal force (N) = 80 N

Frictional force (F) =?

μ = F/N

0.35 = F / 80

Cross multiply

F = 0.35 × 80

F = 28 N

Thus the frictional force is 28 N

Answer:

Option B. 28 N

Explanation:

Answer:

Explanation:

Work done by janitor = increase in potential energy of book

Potential energy = mgh , m is mass  , h is displacement in height and g is acceleration due to gravity .

here displacement in height of book = 2.6 - 1.3 = 1.3 m

so h = 1.3 m

m = mass of the box

increase in potential energy of box = m x 9.8 x 1.3

= 12.74 m

Work done by janitor = 12.74 m Joule .

Answer:

Heredity

Explanation:

Can't change the DNA you inherited the same way you can change eating habits+drug use or avoid stress

Answer:

[tex]\boxed {\boxed {\sf C. \ Heredity}}[/tex]

Explanation:

A risk factor is something that increases the chance of getting a disease. Some are controllable, but some are not.

Stress, eating habits, drug use, exercise, smoking, hygiene, and amount of sleep are all controllable or changeable risk factors. Anybody can change these things in their life.

On the other hand, uncontrollable risk factors, such as age, gender, ethnicity and heredity cannot be changed. Nobody has control over these factors.

So, heredity is the uncontrollable risk factor.

Answer:

friction

Explanation:

the road is the pathway for the vehicle so the tures create friction to stay sturdie

Answer:

b

Explanation:

i just did that question

Answer:

4.61 * 10^-14 m/s ; 9.20 * 10^-10 m/s

Explanation:

To acceleration due to gravity, a

a = GM / r²

Mass of pluto = 1.4x10^22 kg

Distance apart, r = 4.50x10^12 m

G = Gravitational constant = 6.67 * 10^- 11

a = (6.67*10^-11 * 1.4x10^22) / (4.50x10^12)²

a = 9.338 * 10^(-11 + 22) / 20.25x10^24

a = 0.461 * 10^(11 - 24)

a = 0.461 * 10^-13

a = 4.61 * 10^-14 m/s

B.)

Mass of Uranus = 8.62x10^25 kg

Distance apart, r = 2.50x10^12 m

a = (6.67*10^-11 * 8.62x10^25 ) / (2.50x10^12 )²

a = 57.4954 * 10^(-11 + 25) / 6.25x10^24

a = 9.199264 * 10^(14 - 24)

a = 9.199264 * 10^-10

a = 9.20 * 10^-10 m/s

Answer:

67.17 m

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 32 m/s

Angle of projection (θ) = 20°

Acceleration due to gravity (g) = 9.8 m/s²

Range (R) =?

The range can be obtained as follow:

R = u²Sine 2θ / g

R = 32² × Sine (2×20) / 9.8

R = 1024 × Sine 40 / 9.8

R = (1024 × 0.6428) / 9.8

R = 67.17 m

Thus, the range of the ball is 67.17 m

Answer:

[tex]Q'_H=1065kJ/min[/tex]

Explanation:

From the question we are told that

Heat Remove rate Q_o= 750 kJ/min

Power Draw P=5.25

a)Generally the coefficient of performance (COP) of an air conditioner is mathematically given  as

[tex]COP=\frac{Q_o}{P}[/tex]

[tex]COP=\frac{750kJ/min}{5.25kw}[/tex]

Where

[tex]750kJ/min=12.5kJ/sec[/tex]

[tex]COP=\frac{12.5kJ/sec}{5.25kw}[/tex]

[tex]COP=2.38[/tex]

b)Generally the equation for power is mathematically represented as

[tex]P=Q_H-Q_o[/tex]

[tex]P+Q_o=Q_H[/tex]

[tex]Q_H=P+Q_o[/tex]

[tex]Q_H=5.25+12.5[/tex]

[tex]Q_H=17.75kW[/tex]

Generally rate of heat transfer to the outside air is mathematically given as

[tex]Q'_H=17.75*60[/tex]

[tex]Q'_H=1065kJ/min[/tex]

Answer:

Explanation:

From the given information:

The gravitational potential energy at A is:

[tex]PE_A = mgh[/tex]

GIven that:

mass(m) = 3

height (h) = 3

[tex]PE_A =3\times 9.81 \times 3[/tex]

[tex]\mathbf {PE_A =88.29 \ J }[/tex]

b)

Using the conservation of mechanical  energy:

[tex]PE_A+KE_A = PE_B + KE_B[/tex]

[tex]88.29 +0 = 3(9.8)(1) + KE_B[/tex]

[tex]88.29 = 29.4 + KE_B[/tex]

[tex]KE_B = 88.29 -29.4[/tex]

[tex]\mathbf{ KE_B= 58.89 \ J}[/tex]

From the data provided and the calculations done, the potential energy at A is 88.3 J while the kinetic energy at B is 58.9 J.

The potential energy of a body is given as:

where:

m = mass of the object

g = acceleration due to gravity

h = h

At A:

m= 3.0 kg

g = 9.8 m/s^2

h = 3.0 m

PE = 3 × 9.8 × 3

PE = 88.3 J

Kinetic energy, KE of a body is given as:

where:

From the law of conservation of energy, the sum of potential energy and Kinetic energy at every point is equal.

PE + KE at A = PE + KE at B

KE at B = PE + KE at A - PE at B

At A, PE = 88.3 J and KE = 0

At B; h = 1.0 m

PE = 3 × 9.8 × 1

PE = 29.4 J

Therefore, KE at B = 88.3 + 0 - 29.4

KE at B = 58.9 J

Therefore, the potential energy at A is 88.3 J while the kinetic energy at B is 58.9 J.

Learn more about potential energy and Kinetic energy at: https://brainly.com/question/14427111

Answer:

the moment of inertia of the wheel is is 6.245 kg.m²

Explanation:

Given;

applied force, f = 22.04 N

radius of the wheel, r = 0.34 m

angular acceleration, a = 1.2 rad/s²

The moment of inertia of the wheel is calculated as;

[tex]I = \frac{\tau}{\alpha } \\\\I = \frac{Fr}{\alpha } \\\\I = \frac{22.04 \ \times \ 0.34 }{1.2} \\\\I = 6.245 \ kg.m^2[/tex]

Therefore, the moment of inertia of the wheel is is 6.245 kg.m²

Answer:

I. 6 cells .

II. Series connection.

Explanation:

I. Determination of the number of cells needed.

From the question given above,

Total voltage (V) = 9 V

1.5 V = 1 cell

Number of cells needed =?

The number of cells needed to make the 9V battery can be obtained as follow:

1.5 V = 1 cell

Therefore,

9 V = 9 V × 1 cell / 1.5 V

9 V = 6 cells

Thus, 6 cells of 1.5 V each is needed

II. Determination of the connection line

Total voltage (Vₜ) = 9 V

Cell 1 (V₁) = 1.5 V

Cell 2 (V₂) = 1.5 V

Cell 3 (V₃) = 1.5 V

Cell 4 (V₄) = 1.5 V

Cell 5 (V₅) = 1.5 V

Cell 6(V₆ ) = 1.5 V

For parrall connection:

Vₜ = V₁ = V₂ = V₃ = V₄ = V₅ = V₆

9 V = 1.5 V =... = 1.5 V

For series connection:

Vₜ = V₁ + V₂ + V₃ + V₄ + V₅ + V₆

9 = 1.5 + 1.5 + 1.5 + 1.5 + 1.5 + 1.5

9 V = 9 V

From the illustration above, we can see that series connection of each cells will give a total volt of 9 V unlike the parallel connection which resulted to 1.5 V.

Therfore, the cells should be arranged in series connection

Answer:

Distance s  = 90 meter

Explanation:

Given:

Initial velocity u = 0 m/s

Final velocity v = 30 m/s

Acceleration a = 5 m/s²

Find:

Distance s

Computation:

v² = u² + 2as

30² = 0² + 2(5)(s)

Distance s  = 90 meter

Answer:

σ = ±708 nC/m²

Q = ±177 nC

Explanation:

given data

Side of copper plate L = 50 cm

Electric field, E = 80 kN/C

solution

we get here Charge density,σ that is express as

σ = E x ε₀         ....................1

here ε₀ is Permittivity of free space that is 8.85 x 10⁻¹² C²/Nm²

so put value in eq1we get

σ = 80 x 10³ x 8.85 x 10⁻¹²

σ = 708 x 10⁻⁹ C/m²

σ = 708 nC/m²

and

now we get here total change on each faces

Q = σ  A    ...............2

Q = 708 x 10⁻⁹ x (0.50)²

Q = 177 nC

Answer:

C. Methane

Explanation:

A chemical equation can be defined as a reaction between two chemical elements.

For a chemical reaction (equation) to be balanced, the condition which must be met is that the number of atoms contained in the reactants must be equal to the number of atoms in the products.

This ultimately implies that, the mass and charge of the chemical equation are both balanced properly.

Methane is a hydrocarbon compound formed by the reaction between four (4) hydrogen atoms with a carbon atom. It belongs to the alkane group of hydrocarbons and has the following physical and chemical properties; colorless, highly flammable, non-toxic and odorless gas. The empirical formula for Methane is CH4.

Methane is a gas at 45 degrees celsius. This ultimately implies that, at 45°C methane is a gas because it is still within the range of standard temperature and pressure.

a. All go out

b. All get dimmer

c. All get brighter

d. All stay on

Answer:

the power used by the person is 17 W.

Explanation:

Given;

applied force, F = 51 N

distance through which the chair is used, d = 5 m

time of motion, t = 15 s

The power used by the person is calculated as;

[tex]P = FV\\\\P = F \ \times \ \frac{d}{t} \\\\P = 51 \ \times \ \frac{5}{15} \\\\P = 17 \ W[/tex]

Therefore, the power used by the person is 17 W.

Answer:

false

Explanation:

Answer:

Answer is explained in the explanation section below.

Explanation:

Solution:

We know from the Coulomb's Law that, Coulomb's force is directly proportional to the product of two charges q1 and q2 and inversely proportional to the square of the radius between them.

So,

F = [tex]\frac{Kq1q2}{r^{2} }[/tex]

Now, we are asked to get the greatest force. So, in order to do that, product of the charges must be greatest because the force and product of charges are directly proportional.

Let's suppose, q1 = q

So,

if q1 = q

then

q2 = Q-q

Product of Charges = q1 x q2

Now, it is:

Product of Charges = q x (Q-q)

So,

Product of Charges = qQ - [tex]q^{2}[/tex]

And the expression qQ - [tex]q^{2}[/tex] is clearly a quadratic expression. And clearly its roots are 0 and Q.

So, the highest value of the quadratic equation will be surely at mid-point between the two roots 0 and Q.

So, the midpoint is:

q = [tex]\frac{Q + 0}{2}[/tex]

q = Q/2 and it is the highest value of each charge in order to get the greatest force.