Which of the following is an example of a physical change but not a chemical change?
A) The log gives off heat and light as it burns
B) A tree stores energy from the sun in its fruit
C) A penny lost in the grass slowly changes color
D) A water pipe freezes and cracks on a cold night

Answer:

2.25 N upwards

Explanation:

Answer:

800 N/C to the right

Explanation:

The equation that relates force on a charge, electric field and charge is

[tex]F=qE[/tex]

where

F is the force acting on the charge

q is the charge

E is the electric field

In this problem, we have

[tex]E=15 N/C[/tex] is the electric field

[tex]q=-0.15 C[/tex] is the charge

Substituting into the formula, we find the force

[tex]F=(-0.15 C)(15 N/C)=-2.25 N[/tex]

Concerning the direction:

- The electric field and the force have same directions if the charge is positive

- The electric field and the force have opposite directions if the charge is negative

Here the charge is negative, so the electric field has opposite direction to the force: therefore, it must be upwards.

Answer:

Explanation:

The answer is neutrons and protons. The proton for example is composed of 3 quarks with charges of 2/3 + 2/3 - 1/3 which gives an overall  charge of 1.

Neutron are composed of 2 quarks that are - 1/3 in charge and 1 that has a charge of 2/3. The overall charge is 0.

Answer:

Explanation:

Answer:

Multiple transformations occur because the chemical energy of the fuel is changed to several forms of energy

Explanation:

In a car engine, multiple energy transformation takes place. The chemical energy storef in fuel is transformed into mechanical energy which helps move the wheels of the vehicle.

The mechanical energy can also be transformed into electrical energy through a sort of dynamo system in vehicles. Stereo players use the electrical energy to produce sound.

We see that multiple energy conversions are common in a motor car.

Answer:

c

Explanation:

edge

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. It behaves exactly like a permanent magnet, like those magnets commonly used to stick items to our fridge.

To make a permanent magnet we need:

- One iron nail ( Could be fifteen centimeters (6 in) long )

- Three meters (10 ft) of copper wire

- One or more D-cell batteries

To make the electromagnet, we need to:

1. Wrap the Wire Around the Nail

2. Connect the Battery

And you are all set!

Answer:

Correct answer is option C (Brahe and Kepler.)

Explanation:

Copernican model

Copernican model is also known as heliocentric model. According to Copernican model planets rotate around the Sun in an orbit, and earth is orbited  by the Moon. Also sun is  stationary and it lies at the center of the universe and stars also do not move.

Brahe supported the Copernican model  but  he  rejected the idea that earth moves.

Kepler's also supported Copernican model and In his book "the Mysterium Cosmographicum" Kepler appreciated Copernican model. like Kepler also believed in heliocentric model not in  geocentric one.

Answer:

C. Brahe and Kepler

Explanation:

got 100% on pf--- :)))

Answer:

the Hudson Bay was covered with alpine glaciers

Explanation:

During the last glacial period, large portions of North America were covered with ice. The majority of the ice was from the ice sheets that were covering Canada and the northern part of the United States, and the alpine glaciers on the mountain ranges. Hudson Bay was all frozen at this point of time. It was not covered with alpine glaciers though, instead it was covered with the ice of the extended ice sheets, with the ice cover reaching up to 2 km in thickness.

Opposite Poles in Magnets Attract Each-other

Answer:15 newton force is required.

Explanation:

We know that

Force equal to mass x acceleration

3 kg x5 m/ s square

15( kg x m/s square)

15( newton)

15 N

The amount of force that is needed to accelerate a 3 kg skateboard at 5 m/s² is 15N

According to Newton's second law of motion, the formula for calculating the force required to accelerate an object is expressed as;

F = ma

m is the mass of the object

a is the acceleration

Given the following parameters

Mass = 3 kg

Acceleration = 5m/s²

Get the required force:

F = 3 * 5

F = 15 N

Hence the amount of force that is needed to accelerate a 3 kg skateboard at 5 m/s² is 15N

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Answer:

Step By Step Explanation:

Answer:

i think it is c

Explanation:

Answer:its plywood

Explanation:i just took the test

Answer:

0.4 m/s

Explanation:

First of all, let's find the frequency of the wave, which is equal to the reciprocal of its period:

[tex]f=\frac{1}{T}=\frac{1}{5 s}=0.2 Hz[/tex]

Now we can find the wave speed using the formula:

[tex]v=f\lambda[/tex]

where

f = 0.2 Hz is the frequency

[tex]\lambda=2 m[/tex] is the wavelength

Substituting, we find

[tex]v=(0.2 Hz)(2 m)=0.4 m/s[/tex]

Answer:

800 N/C to the right

Explanation:

The relationship between electric force, electric field and charge is

[tex]E=\frac{F}{q}[/tex]

where

E is the electric field

F is the force acting on the charge

q is the charge

In this problem, we have

[tex]F = 0.040 N[/tex] is the force

[tex]q=+50 \mu C=+50 \cdot 10^{-6}C[/tex] is the charge

Substituting into the formula, we find the electric field magnitude

[tex]E=\frac{0.040 N}{+50 \cdot 10^{-6}C}=800 N/C[/tex]

Concerning the direction:

- The electric field and the force have same directions if the charge is positive

- The electric field and the force have opposite directions if the charge is negative

Here the charge is positive, so the electric field has same direction as the force: therefore, to the right.

Answer:

paper burned and turned into smoke...

Explanation:

When a chemical reaction has taken place that means that whatever the starting variable is, (in this case it was the paper) then it cannot go back to its original state... you can also tell if a chemical reaction has taken place if the test releases any kind of gas, if there is a temperature change, or if there is a color change. Which this time it changed from paper into smoke which is a gas

Hope This Helps

Answer:

paper burned and turned into smoke

Explanation:

Because it changes how i looks and the chemichals change.

Answer:

A. polymerization

Explanation:

Synthetic plastics are made by linking many simple carbon molecules together to form much larger molecules. This process is called polymerization.

Synthetic or artifical giant molecules consists of synthetic polymers such as plastics, elastomers etc. They are made up of simple monomers which links to form the complex and giant structure.

Monomers are the simplest unit of polymers. Polymers have very great sizes. The size mkaes their structure quite complex. This makes the molecules more disposed in a regular pattern with respect to one another.

The complexity of structure and the attendant effects accounts for the properties and uses that makes synthetic molecules very unique. For example, plastics can be extruded as sheets, pipes and or moulded into other objects.

Answer:

A. Polymerization

Explanation:

Penn Foster

The answer is: B a meteorite

The answer is B which is a meteorite.

Answer:

9.26 cm, 22.7 cm, 3.20 m/s

Explanation:

In a plane mirror, the image and object have the same height.  So h = 9.26 cm.

In a plane mirror, the image distance is the same as the object distance.  So x = 22.7 cm.

Since the distance between an object and a plane mirror is the same as the distance between the mirror and the image, then the distance between you and the image is double the distance between you and the mirror.  If you move away from the mirror at 1.60 m/s, the image will move away from you at double that speed, or 3.20 m/s.

Answer:

100.2 kg

Explanation:

The period of vibration of a spring-mass system is given by

[tex]T=2\pi \sqrt{\frac{m}{k}}[/tex]

where

T is the period

m is the mass

k is the spring constant

In this problem, we know

T = 1.419 s is the period

k = 1962 N/m is the spring constant

Re-arranging the equation, we can find the mass:

[tex]m=k(\frac{T}{2\pi})^2=(1962 N/m)(\frac{1.419 s}{2\pi})^2=100.2 kg[/tex]

Answer:

Magic school bus on ya left! so basically a star is born when like....atoms are like squeezed with enough pressure and kinda squished together, once tht happens the atoms start to fuse together

Explanation:

A star is born when nuclear fusion reactions begin in its core, transforming a protostar into a stable, shining star. This occurs in giant clouds of gas and dust called nebulae.

The birth of a star marks the moment it becomes hot enough for nuclear fusion reactions to take place at its core. This process begins in giant, cold clouds of gas and dust called nebulae. As the cloud collapses under its own gravity, it forms a protostar.

When the core temperature of the protostar reaches about 10 to 12 million K, hydrogen atoms begin to fuse into helium, releasing vast amounts of energy and causing the star to shine. This fusion marks the birth of a new star, which then becomes stable and enters what is known as the main sequence phase of its life, where it spends most of its time.

In simpler terms, the birth of a star is the point at which it starts producing its own energy through fusion, much like a human child begins to sustain itself independently after birth.

Answer:

Zeros to the left of a decimal can be insignificant place holders, such as in 0.043 (two significant figures).

They can be significant if they are between two digits who themselves are significant, such as in 101.000 (three significant figures).

In the case of a number like 1,000 we can see there is only one significant figure. The zero digits are not between sigfigs.

Answer:

Zeros to the left of a decimal can be insignificant place holders, such as in 0.043 (two significant figures).

They can be significant if they are between two digits who themselves are significant, such as in 101.000 (three significant figures).

In the case of a number like 1,000 we can see there is only one significant figure. The zero digits are not between sigfigs.\

Answer: The answer is C. 4.9 sec.

Explanation:

Answer:

c) 4.9 s

Explanation:

Young's modulus of aluminium is given as

[tex]Y = 69 \times 10^9 pa[/tex]

density of aluminium is given as

[tex]\rho = 2700 kg/m^3[/tex]

now the speed of sound in aluminium is given as

[tex]v = \sqrt{\frac{Y}{\rho}}[/tex]

[tex]v = \sqrt{\frac{69 \times 10^9}{2700}}[/tex]

[tex]v = 5055.3 m/s[/tex]

now the time taken by the sound to travel a distance of d = 25 km

[tex]t = \frac{d}{v}[/tex]

[tex]t = \frac{25 \times 10^3}{5055.3}[/tex]

[tex]t = 4.9 s[/tex]

Answer:

age structure

Explanation:

The variable would be most useful in determining the number of people eligible for retirement benefits in a certain year is age criteria.

When an employee reaches his age of retirement from work, he needs to stay at home and perform no work in organization.

So, the age criteria is an important factor to decide the retirement of a person. He is then eligible for all the retirement benefits offered by the private sector organization or government.

Thus, variable would be most useful in determining the number of people eligible for retirement benefits in a certain year is age criteria.

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Explanation:

The given data is as follows.

        Final velocity (v) = 8.62 m/s,         Initial velocity ([tex]v_{o}[/tex]) = ?

         time = 8.25 sec,          distance (s) = 12.9 m

Hence, formula to calculate the initial velocity is as follows.

                   v = [tex]v_{o} + a \times t[/tex]

                 8.62 m/s = [tex]v_{o} + a \times 8.25 s[/tex]

                [tex]v_{o}[/tex] = 8.62 m/s - 8.25a ......... (1)

Also,   s = [tex]v_{o} \times t + \frac{1}{2}a \times t^{2}[/tex] ...... (2)

Therefore, substitute the value of [tex]v_{o}[/tex] from equation (1) into equation (2) as follows.

                s = [tex]v_{o} \times t + \frac{1}{2}a \times t^{2}[/tex]

               s = [tex]8.62 m/s - 8.25a \times t + \frac{1}{2}a \times t^{2}[/tex] ....... (3)  

Now, putting the values of s and t into equation (3) as follows.

         s = [tex]8.62 m/s - 8.25a \times t + \frac{1}{2}a \times t^{2}[/tex]  

        12.9 m = [tex](8.62 m/s - a \times 8.25sec) \times 8.25 s + \frac{1}{2}a \times (8.25 sec)^{2}[/tex]  

               a = 1.71 [tex]m/s^{2}[/tex]  

Therefore, using equation (1) the value of initial velocity will be as follows.

                      [tex]v_{o}[/tex] = [tex]8.62 m/s - 8.25 sec \times a[/tex]

                              = [tex]8.62 m/s - 8.25 sec \times 1.71 m/s^{2}[/tex]

                              = -5.49 m/s

Thus, we can conclude that starting velocity of the car is -5.49 m/s.

Answer:

-5.49 m/s

Explanation:

I just had this same question on my Acellus Academy physics course for 9th grade. Hope this helps ;)

Answer:

Because the gravitational attraction of the Sun hold them in motion around it

Explanation:

For an object travelling in a straight path at constant velocity, the net force acting on the object must be zero.

The planets in the Solar System, however, do not experience a zero net force: in fact, the Sun exerts a gravitational attraction on them, whose magnitude is given by

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

where

G is the gravitational constant

M is the mass of the Sun

m is the mass of the planet

r is the average distance between the Sun and the planet

Due to the presence of this force, the Sun makes the planets 'deviating' from their straight path, forcing them to following an elliptical path around the Sun.

I believe it is the Cassiopeia. It is visible during winter in the early part of the night. It look like a distorted letter W or M.

I am not very sure of it though, I apologize if this is not what you meant.

Answer:

Ursa Minor Constellation

Explanation:

Ursa Minor constellation lies in the northern sky. The constellation's name means “the smaller bear,” or “the lesser bear,” in Latin. The Great Bear constellation is represented by its larger neighbor Ursa Major.

The displacement from point A to point B is the length of the shortest path between them along with the direction from A to B.

Choice D

When a body is moving on a linear path, the displacement is the shortest path between two points, including both distance and direction. The correct option is D.

The distance is the total path traveled by the particle or an object on a linear path.

When the particle has moved from point A to B straight on the path, the distance is equal to the displacement. When the particle takes a U turn or deflects from the path to left or right or any direction, the displacement is less than the distance. The displacement is measured as the distance between the initial and final point.

Thus, when a body is moving on a linear path, the displacement is the shortest path between two points, including both distance and direction. The correct option is D.

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Answer:

Blue-green bacteria or cynobacteria belong to the kingdom Monera

Blue-green bacteria belongs to the kingdom

a. Monera.

Answer: For number 9, the children would not be able to close the box.

Explanation: The combined force of the children is 55 N. The box spring overpowers them with 60 N. I hope this helps!

because if the bus goes to stop or go that person would be injured badly that is y the bus driver tells u to sit down

Most of the weight of standees is from their feet, which are on the floor, so they should be raising the center of gravity much.

I think just the added weight of standees makes the bus suspension less able to control sway and lean. Going into a curve or skid with more passengers means a better chance of rolling.

I've taken some curves with what we called a "full swinging load" that made my hair stand on end the bus leaned over so far.

Really busses can lean pretty far without going over. Another fun thing is if the air suspension bellows blow out on one side or a front tire blows out. Definitely gets your attention and not just because the passengers are screaming.

Going back to center of gravity, if the bus sways or leans on a curve and more of the passengers weight is transferred to the overhead bar that might make a difference, once the lean gets bad because of the weight in general.

Answer:

Explanation:

That is exactly what it does. That's how it is set up.

True

An electrocardiogram (ECG or EKG) is a diagnostic tool used to record the electrical activity of the heart. It involves the use of an electrocardiograph and electrodes. However, it has certain limitations and cannot reveal the effectiveness of the heart's pumping action.

An electrocardiogram (ECG), also often abbreviated as EKG, is a recording of the electrical activity of the heart that can be used to diagnose irregular heart function. Through the placement of surface electrodes on the body, the complex, compound electrical signal of the heart can be recorded. These signals are created from the processes of depolarization and repolarization, especially in the heart.

The standard electrocardiograph uses between 3 and 12 leads to capture this information. These leads may refer to the cables from the electrodes to the electrical recorder, but typically, it refers to the voltage difference between two electrodes. Sometimes, a patient might need to wear a portable device known as a Holter monitor to continuously monitor the heart's electrical activity.

It's important to note that the ECG has limitations. For instance, not all areas suffering a myocardial infarction (MI) may show up on the ECG. It also will not reveal the effectiveness of the heart's pumping action, which requires further tests such as an echocardiogram or nuclear medicine imaging.

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B would be most reasonable

The average speed of Joe's fastball correct SI unit is m/s.

Answer: C

Explanation

According to the problem given, the baseball thrown by Joe reaches the catcher's glove within the blink of audience's eyes.

Generally, human beings tend to blink their eyes every second to some minutes.

So as the ball reaches the catcher's glove within blink of eye that means the motion of the ball starting from thrown by Joe and ending at catcher's glove is completed within seconds. So the speed of the ball is in seconds.

As the catcher will be positioned at some meter distance so the distance traveled will be in meter in SI unit.

So the rate of change of distance per unit second is termed as velocity.

Thus the average speed will be recorded in m/s unit.