7. Which phase changes require a gain of energy (heat)?
a. melting and freezing
b. sublimation and vaporization
c. vaporization and condensation
d. sublimation and deposition

Answer:

this has to do with the drop in voltage, or potential as electrons traverse the material .

Answer:

29.41%

Explanation:

Given that,

In 1630 at the beginning of European settlement, about 425,000,000 hectares of the United States were covered with trees.

By 2017, the area covered by trees was reduced to 300,000,000 hectares.

We need to find the percentage decrease in the area covered by trees between 1630 and 2017.

The percentage decrease in any value is given by :

[tex]\%=\dfrac{300,000,000 -425,000,000 }{425,000,000 }\times 100\\\\=29.41\%[/tex]

So, the percentage decrease in the area covered by the trees is 29.41%.

Answer:

104 N

Explanation:

m = 1300 kg

a = 0.08m/s^2

F = 1300*0.08

F = 104 N

Newtons is the unit of force.

Explanation:

acceleration is the Changing of throut per unit time ....

and in uniform motion .....

in that the speed of an object is uniform means same

Unit to measure red blood cell is million per cubic millimeter

A red blood cell, also called a hematopoietic cell, hemocyte, is a cell produced through hematopoiesis and found mainly in the blood

Unit to measure red blood cell is million per cubic millimeter

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Answer:

Change in the magnetic field

Answer:

10.791 kJ

Explanation:

Given that,

Mass of the skier, m = 58 kg

Initial position, h₁ = 24 m

Final position, h₂ = 19 m

We need to find the kinetic energy do they have at the top of the second hill.

Using the conservation of energy for both positions.

[tex]v_1=\sqrt{2gh_1} \\\\=\sqrt{2\times 9.8\times 24} \\\\=21.68\ m/s[/tex]

And

[tex]v_2=\sqrt{2gh_2} \\\\=\sqrt{2\times 9.8\times 19} \\\\=19.29\ m/s[/tex]

Kinetic energy :

[tex]K=\dfrac{1}{2}mv_2^2\\\\K=\dfrac{1}{2}\times 58\times 19.29^2\\\\=10791.01 J\\\\=10.791\ kJ[/tex]

So, the kinetic energy they have at the top of the second hill is 10.791 kJ.

Answer:

10 N

Explanation:

Force = Mass÷Acceleration

F= 50 ÷ 5

= 10 N

______________________

Acceleration =

[tex] \frac{5 - 25}{4 } [/tex]

= 5m/s2

Given:

As we know,

The acceleration will be:

= [tex]\frac{5-25}{4}[/tex]

= [tex]5 \ m/s^2[/tex]

hence,

The force will be:

→ [tex]F = \frac{m}{a}[/tex]

By substituting the values, we get

      [tex]= \frac{50}{5}[/tex]

      [tex]= 10 \ N[/tex]

Thus the above response is right.  

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Answer:

They are reflected.

Explanation:

Red light is absorbed while green light is reflected, causing the color to be green in human eyes.

Answer:

C

Explanation:

Answer:

from second equation of motion

[tex]S = ut + \frac{1}{2} a {t}^{2} \\ S = (50 \times 20) + (\frac{1}{2} \times 3 \times {20}^{2} ) \\ S = 1000 + 600 \\ S = 1600 \: m[/tex]

Explanation:

The reason for this phenomenon is the due to the condition by which each type of rocks form.

A sedimentary rock is formed by the compaction and lithification of sediments within a basin.

A metamorphic rock forms under high temperature and pressure conditions which alters the minerology of a rock.

Answer:

The heat and pressure of metamorphism would deform the fossil, and the process of melting would destroy the fossil completely.

Explanation:

PLATO

Answer:

Solution in photo

Explanation:

A car moves around in a circular racing track, and it takes 120 seconds to do a lap of 8 km, so the speed in km/hr is 239.76 km/hr.

The speed of an object, commonly known as v in mechanics, is a scalar quantity that corresponds towards the size of the change in that object's position over duration or the size of the change in that object's position per unit of time.

The instantaneous velocity is the absolute maximum of the average speed as the time interval's duration gets closer to zero. The cruising pace of an object in a time interval is calculated by dividing its distance traveled by the time interval's duration. Velocity and speed are different concepts.

The given data according to the question is,

Time, t = 120 s

Distance, d = 8 km

s = 8/120

s =0.0666 km/sec or

s = 0.0666/1s × 3600

s = 239.76 km/hr.

Therefore, the speed is 239.76 km/hr.

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Answer:

Without volcanoes, most of Earth's water would still be trapped in the crust and mantle . Early volcanic eruptions led to the Earth's second atmosphere, which led to Earth's modern atmosphere . Besides water and air, volcanoes are responsible for land, another necessity for many life forms .

Explanation:

Answer:

A

Explanation:

C = (F-32)*5/9 = 73*5/9 = 40.55555

since the answers are spread apart, technically you can just estimate by doing -32

and then /2

since 5/9 is close to 1/2

Answer:

c

Explanation:

energy doesnt affect to mass of a object

Answer:

the answer is 104568948 degress

Explanation:

yeeeeeee

Answer:

hope this answers will help you

Explanation:

If you find it appropriate then plz mark as brainliest

Answer: 0.83333333333 km/h

Explanation: give brainliest

Answer:

Movement

Explanation:

Answer:

..

Charcoal is flammable.

AnswerShe uses force and air

Explanation:

n bhvygvg gv

Answer:

without oxygen because

Answer:

Without oxygen

Explanation:

Answer:

bowling

Explanation:

bowling is an example of work because it involves hand movement.

Answer:B

Explanation:i think so im not suree

A sailboat that is tied up at the dock will experience tension force and gravity. Therefore, option (D) is correct.

Tension can be described as a force acting along the flexible length of a medium such as a rope, string, or cable, or a force carried by a flexible medium.

Tension can be defined as an action-reaction pair acting at each end of the elements. For a rope, tension is present in every section of the rope or string in both directions, apart from their endpoints. Each endpoint of the rope will experience tension and force from the weight attached to it.

Tension can also be defined as a pulling force but the tension is not a pushing force. Ropes or strings are used to exert forces since they transfer a force over a specific distance.

Therefore, sailboats experience the tension force due to the rope with which it is tied at the dock and the force due to gravity.

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Answer:

The velocity of the nickel just before it hits the ground is approximately 49.3 m/s

Explanation:

In order to calculate the velocity of the nickel just before it hits the ground, we recall the kinematic equation of motion, v² = u² + 2·g·h, where the variables of the equation are defined as follows;

v = The velocity of the nickel just before it hits the ground after it is pushed off the observation deck

u = The initial velocity of the nickel just before it is pushed off the observation deck = 0 m/s

g = The acceleration due to gravity = 9.8 m/s²

h = The height from which he nickel is pushed off the edge = 124 m

Substituting the given values and the constant, "g", we have;

v² = 0² + 2 × 9.8 × 124 = 2,430.4

v = √2,430.4

Using a graphing calculator, we have;

v = √2,430.4 = 14·√(62/5) ≈ 49.3

The velocity of the nickel just before it hits the ground = v ≈ 49.3 m/s.

Answer:Two dimensional forms can create the illusion of 3 dimensional shapes and spaces.

Explanation:

First thing's first, we need to find the Net Force of the system in order to solve for acceleration. Gravity and Normal Force cancel out, so we don't really have to worry about anything on the y-axis. However, looking at the x-axis, we see two forces: the Force of the push and Frictional Force.

This means that:

[tex]F_{net}[/tex] = 500 - 100

[tex]F_{net}[/tex] = 400 (N)

Recall that Force = Mass * Acceleration. Since we have the Force and Mass, we can easily solve for Accel:

F = ma

a = [tex]\frac{F}{m}[/tex]

Plug the net force and mass into the equation:  

a = [tex]\frac{F}{m}[/tex]

a = [tex]\frac{400}{50}[/tex]

a = 8 (m/[tex]s^{2}[/tex])

The box's acceleration is 8 m/[tex]s^{2}[/tex]

If you have any questions about how I got to the answer, just ask :)

Answer:

B

Polar covalent bonds and van dar Waals forces are weak attractive forces between discrete molecules of a simple molecular structure.

Ionic bonds are strong electrostatic forces of attraction between oppositely charged ions.

Hydrogen bonds are very strong bonds between hydrogen and a highly electronegative atom e.g Oxygen, fluorine, nitrogen

Answer:

Tension = 2.5 N

Explanation:

Given:

Angle = 60°

Force f = 5 N

Find:

Tension

Computation:

Tension = fcosθ

Tension = (5)cos60

Tension = (5)(1/2)

Tension = 2.5 N