Question 4 of 10
Which two options are reasons that electromagnetic waves are effective for
use in communication devices?
A. The entire electromagnetic spectrum can be used.
B. They can travel through matter and through space.
C. Both gamma rays and X-rays can be used.
D. They can carry information for long distances without wires.

Answer:

Assume that [tex]g =9.81\; \rm m\cdot s^{-1}[/tex], and that the air resistance on the stone is negligible.

a.

Height of the stone: [tex]389.5\; \rm m[/tex] (above the ground.)

Velocity of the stone: [tex]\left(-110.5\; \rm m \cdot s^{-1}\right)[/tex] (the stone is travelling downwards.)

b.

Height of the stone: [tex]629.5\; \rm m[/tex] (above the ground.)

Velocity of the stone: [tex]\left(-86.5\; \rm m \cdot s^{-1}\right)[/tex] (the stone is travelling downwards.)

Explanation:

If air resistance on the stone is negligible, the stone would be accelerating downwards at a constant [tex]a = -g = -9.81\; \rm m \cdot s^{-2}[/tex].

Let [tex]h_0[/tex] denote the initial height of the stone (height of the stone at [tex]t = 0[/tex].)

Similarly, let [tex]v_0[/tex] denote the initial velocity of the stone.

Before the stone reaches the ground, the height [tex]h[/tex] (in meters) of the stone at time [tex]t[/tex] (in seconds) would be:

[tex]\displaystyle h(t) = -\frac{1}{2}\, g \cdot t^{2} + v_0 \cdot t + h_0[/tex].

Similarly, before the stone reaches the ground, the velocity [tex]v[/tex] (in meters-per-second) of the stone at time [tex]t[/tex] (in seconds) would be:

[tex]v(t) = -g\cdot t + v_0[/tex].

In section a., [tex]h_0 = 1000\; \rm m[/tex] while [tex]v_0 = -12\; \rm m\cdot s^{-1}[/tex] (the stone is initially travelling downwards.) Evaluate both [tex]h(t)[/tex] and [tex]v(t)[/tex] for [tex]t = 10\; \rm m \cdot s^{-1}[/tex]:

[tex]\begin{aligned} h(t) &= -\frac{1}{2}\, g \cdot t^{2} + v_0 \cdot t + h_0 \\ &= -\frac{1}{2}\ \times 9.81\; \rm m\cdot s^{-2}\times (10\; \rm s)^{2} \\&\quad\quad + \left(-12\; \rm m \cdot s^{-1}\right) \times 10\; \rm s + 1000\; \rm m \\[0.5em] &= 389.5\; \rm m \end{aligned}[/tex].

Indeed, the value of [tex]h(t)[/tex] at [tex]t = 10\; \rm m \cdot s^{-1}[/tex] is greater than zero. The stone hasn't yet hit the ground, and both the representation for the height of the stone and that for the velocity of the stone are valid.

[tex]\begin{aligned} v(t) &= -g\cdot t + v_0 \\ &= -9.81\; \rm m\cdot s^{-2}\times 10\; \rm s - 12\; \rm m\cdot s^{-1} \\ &= -110.5\; \rm m \cdot s^{-1} \end{aligned}[/tex].

The value of [tex]v(t)[/tex] at [tex]t = 10\; \rm m \cdot s^{-1}[/tex] is negative, meaning that the stone would be travelling downwards at that time.

In section b., [tex]h_0 = 1000\; \rm m[/tex] while [tex]v_0 = 12\; \rm m\cdot s^{-1}[/tex] (the stone is initially travelling upwards.) Evaluate both [tex]h(t)[/tex] and [tex]v(t)[/tex] for [tex]t = 10\; \rm m \cdot s^{-1}[/tex]:

[tex]\begin{aligned} h(t) &= -\frac{1}{2}\, g \cdot t^{2} + v_0 \cdot t + h_0 \\ &= -\frac{1}{2}\ \times 9.81\; \rm m\cdot s^{-2}\times (10\; \rm s)^{2} \\&\quad\quad + 12\; \rm m \cdot s^{-1} \times 10\; \rm s + 1000\; \rm m \\[0.5em] &= 629.5\; \rm m \end{aligned}[/tex].

Verify that the value of [tex]h(t)[/tex] at [tex]t = 10\; \rm m \cdot s^{-1}[/tex] is indeed greater than zero.

[tex]\begin{aligned} v(t) &= -g\cdot t + v_0 \\ &= -9.81\; \rm m\cdot s^{-2}\times 10\; \rm s + 12\; \rm m\cdot s^{-1} \\ &= -86.5\; \rm m \cdot s^{-1} \end{aligned}[/tex].

Similarly, the value of [tex]v(t)[/tex] at [tex]t = 10\; \rm m \cdot s^{-1}[/tex] is negative because the stone would be travelling downwards at that time.

Answer:

Troposphere

High-pressure areas form due to downward motion through the troposphere, the atmospheric layer where weather occurs.

Answer:

l

Explanation:

Answer:

true I believe

Explanation:

Answer:

Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. Inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.

Explanation:

Hope this helps      :)

Answer:

does work have to be done to hold the object in place

Answer:

Does the object move when it is released from a rest position? and Does a force act on the object?

Explanation:

i had the same quiz today and the other 2 are wrong

Answer:

the one made from aluminum

Explanation:

Answer:

3683.67 m

Explanation:

Formula for maximum height of projectile is given by the equation;

h = u²/2g

Where u is initial velocity and g is acceleration due to gravity

We are given u = 190 m/s

Thus;

h = 190²/9.8

h = 36100/9.8

h = 3683.67 m

Answer:

953.5 J/kg.°C

Explanation:

From the question,

Heat lost by the metal = heat gained by the glass.

cm(t₁-t₃) = c'm'(t₃-t₂)................. Equation 1

Where c = specific heat capacity of the metal, m = mass of the metal, c' = specific heat capacity of the glass, m' = mass of the glass, t₁ = initial temperature of  metal, t₂ = initial temperature of glass, t₃ = Equilibrium temperature

Make c' the subject of the equation

c' = cm(t₁-t₃)/m'(t₃-t₂)................ Equation 2

Given: m = 5 kg, c = 650 J/kg.°C, m' = 1.25 kg, t₁ = 80 °C, t₂ = 20 °C, t₃ = 63.9 °C

Substitute these values into equation 2

c' = 5×650(80-63.9)/1.25(63.9-20)

c' = (5×650×16.1)/(1.25×43.9)

c' = 52325/54.875

c' = 953.5 J/kg.°C

Answer:

960 J/(kg*C)

Explanation:

i got this right in acellus  trust me :D

Answer:

It is negativity charged

Answer:

positively charged

Explanation:

a wool has neutral charges hence when rubbed against a balloon it will generate positive charges

i think this is the incomplete page that you are showing but the answer is

:-

Answer:

The relation between velocity and time is a simple one during uniformly accelerated, straight-line motion. The longer the acceleration, the greater the change in velocity. Change in velocity is directly proportional to time when acceleration is constant.

~Hoped this helped~

~Brainiliest?~

Answer:

We describe motion in terms of velocity and acceleration. Velocity: The rate of change of displacement of an object (displacement over elapsed time) is velocity. Velocity is a vector since it has both magnitude (called speed) and direction. ... Acceleration: The rate of change of velocity is acceleration.

Explanation:

Displacement is a vector which points from the initial position of an object to its final position. ... Instantaneous velocity, on the other hand, describes the motion of a body at one particular moment in time. Acceleration is a vector which shows the direction and magnitude of changes in velocity.

Displacement is the vector difference between the ending and starting positions of an object. Velocity is the rate at which displacement changes with time. ... The average velocity over some interval is the total displacement during that interval, divided by the time.

Hope this helps      :)

Answer:

Centrifugal force = 1230.77 Newton.

Explanation:

The force associated with the car is generally referred to as centrifugal force and it can be calculated using the formula;

Centrifugal force = mv²/r

Given the following data;

Mass = 800kg

Radius = 65m

Velocity = 10m/s

To find the force;

Centrifugal force = (800*10²)/65

Centrifugal force = (800*100)/65

Centrifugal force = 80000/65

Centrifugal force = 1230.77 Newton.

Answer:

If a coil of wire is placed in a changing magnetic field, a current will be induced in the wire. This current flows because something is producing an electric field that forces the charges around the wire. (It cannot be the magnetic force since the charges are not initially moving). ... that determines the induced current.

Answer; Sodium 2-Aminopentanedioate The chemical formula of MSG is C5H8NO4Na and its IUPAC name is sodium 2-aminopentanedioate. Since it is known to intensify meaty flavours in food, monosodium glutamate is widely used as a flavour enhancer in the food industry. This compound was first produced by the Japanese chemist Kikunae Ikeda in the year 1908.

Explanation:

Answer:

=(220^2 +150^2)

/

put this on a square root

for you to get 266.2705391

round it to a whole number =266km/h

Explanation:

p

Answer:

A) rational kinetic energy is conserved

For the scenario painted below Rational kinetic energy is conserved

Option A is correct

Kinetic energy is simply defined as the energy that an item or particle has as a result of its movement.

In conclusion, For A longboard is free to slide on a sheet of frictionless ice. and a skater skates to the board and hops onto one end, causing the board to slide and rotate. In this situation Rational kinetic energy is conserved

Read more about Kinetic energy

https://brainly.com/question/999862

Answer:

nuclear energy

Explanation:

Answer:

Impulse = 4Ns

Explanation:

Given the following data;

Force = 2N

Time = 2 seconds

To find the impulse experienced by the object;

Impulse = force * time

Impulse = 2*2

Impulse = 4Ns

Therefore, the impulse experienced by the object is 4 Newton-seconds.

Answer:

38 cm from q1(right)

Explanation:

Given, q1 = 3q2 , r = 60cm = 0.6 m

Let that point be situated at a distance of 'x' m from q1.

Electric field must be same from both sides to be in equilibrium(where EF is 0).

=> k q1/x² = k q2/(0.6 - x)²

=> q1(0.6 - x)² = q2(x)²

=> 3q2(0.6 - x)² = q2(x)²

=> 3(0.6 - x)² = x²

=> √3(0.6 - x) = ± x

=> 0.6√3 = x(1 + √3)

=> 1.03/2.73 = x

≈ 0.38 m = 38 cm = x

Inner Planets:

- Rocky

- Small

- Only 3 moons total

- Very close to each other (for space)

- Underweight

Outer Planets:

- Gassy oop-

- GIANT

- Over 200 moons total

- VERY far from each other

- Obese

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Good luck foe.

Lb.

Answer:

50 N

Explanation:

We are given;

Force on larger piston; F2 = 5000 N

Ratio of diameter of smaller piston to larger piston = 1:10

Now, formula for force on smaller piston which we will denote with F1 is gotten from;

F1 = F2 × A1/A2

Now, A1 = π(d1)²/2

A2 = π(d2)²/2

Thus:

F1 = F2 × (π(d1)²/2)/(π(d2)²/2)

This gives;

F1 = F2 × (d1/d2)²

Plugging in the relevant values;

F1 = 5000 × (1/10)²

F1 = 50 N

A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently.

Answer:

A switched-mode power supply (switching-mode power supply, switch-mode power supply, switched power supply, SMPS, or switcher) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently.

Explanation:

Answer:

the answer is all of the above

Explanation:

brainliest please

Answer:

sound waves

Explanation:

this is because sound waves are longitudinal waves, and longitudinal waves are waves that travel parallel to the direction of the wave motion

thus it cannot be light or electromagnetic waves but only sound waves

hope this helps, please mark it

Answer:

Studies show that eating fewer animal-based products could reduce water use since animal production uses more water than crops do. In addition, reducing the amount of food that's lost or wasted at various points in the food supply chain could feed about 1 billion extra people while simultaneously reducing water use.

Answer:

the force of gravity acting between the earth and any other object is directly proportional to the mass of the earth, directly proportional to the mass of the object, and inversely proportional to the square of the distance that separates the centers of the earth and the object.

Explanation:

Answer:

H-Hydrogen

B-Boron

O-Oxygen

Au-Gold

Co-Cobolt

He-Helium

Na-Sodium

S-Sulfur

K-Potassium

Ag-Silver

Explanation:

Normally, chemical symbols are either the first letter or the first two letters of the element.

However, there are some exceptions where they use the Latin names e.g:

Aurum-Au-Gold

Natrium-Na-Sodium

Kalium-K-Potassium

Argentum-Ag-Silver

Hope this helps :)