Injuries can be prevented if you follow the rules, use protective equipment, and know the risks of injuries involved in each sport. Please select the best answer from the choices provided. T F

D. Atoms.

Explanation:

All the matter is made of elementary particles called "atoms".

Further, an atom is made of electrons, protons and neutrons. The electrons & protons are again made of the fundamental sub-particles, electrons (leptons) and the protons(quarks).

The classification of particles is shown in the figure attached

D. Atoms.

Because different kinds of atom have different number of protons, neutrons, and electrons.

Answer: C. illuminance of a surface.

a)  Incandescence:  The phenomenon of light emission by a body as a result of high temperature.

B. Luminous flux :  It is the quantity of the energy of the light emitted per second in all directions.

C. Illuminance of a surface :describes the quantity of light emitted by a light source or received at a surface.

D. luminous intensity : the quantity of visible light that a point source radiates in a given direction.

Final answer:

To determine the average number of neutrons in an element, subtract the atomic number from the atomic mass listed on the periodic table. For elements with no stable isotopes, the number in square brackets is used for the most stable isotope. Note that the atomic mass is the average mass reflecting the mixture of isotopes found in nature.

Explanation:

To determine the average number of neutrons in an element using the periodic table, you can look at two quantities for each element: the atomic number and the atomic mass. The atomic number, which is the whole number listed with the element, represents the number of protons in the nucleus. The atomic mass (or mass number) is listed with a decimal and represents the average mass of all the isotopes of that element, taking into account the natural abundance of each isotope. It is effectively the average number of protons and neutrons combined.

To calculate the average number of neutrons, you would subtract the atomic number from the atomic mass. For elements with no stable isotopes (such as technetium, promethium, polonium, and those higher than atomic number 84), the mass number in square brackets indicates the mass of the most stable (often hypothetical) isotope. It is important to note that the atomic mass on the periodic table is usually not a whole number because it accounts for the average atomic mass of the naturally occurring isotopes.

Out of the following given choices;

A) It is always difficult to get a project like this approved. This study will help them convince the local community to support the project.

B) If they do not perform the study, and there is a problem during the dredging project, the media could make them look bad.

C)The study will weigh the benefits against the negative impacts so an informed decision can be made.

D)The study will demonstrate the local government's concern for the community's safety.

The answer is; C

Dredging can have a negative impact on the marine environment. Destruction of this ecosystem could have reverberating effects that affect the communities that rely on this ecosystem for livelihoods, such as fishermen. An environmental and feasibility study will help weigh the benefits and demerits of the project and allow for an informed decision to be made.  

Answer:

I believe the answer Is C

Explanation:

I got it right on my test

Answer:

5.7 m/s^2

Explanation:

First of all, we need to calculate the resultant force on the crate. We have:

- A force of +210 N in the positive direction

- The frictional force of -74 N in the opposite direction

So, the resultant force is

F = 210 N - 74 N= 136 N

So now we can apply Newton's second law to find the acceleration:

[tex]F=ma[/tex]

where m=24 kg is the mass of the crate. Re-arranging the equation, we get:

[tex]a=\frac{F}{m}=\frac{136 N}{24 kg}=5.7 m/s^2[/tex]

Power is work divided by time or in other words power is juels per second and work is juels

Answer: The unit of work is Joule and Unit for power is Watt which is equal to Joule per second.

Explanation: Work is defined as the unbalanced force which displaces an object. It is also defined as the energy consumed. The units of work is Joules.

Mathematically,

[tex]W=F.d[/tex]

Power is defined as the work done per unit time. The unit of power is Joules per second. The S.I. unit of this is Watt.

Mathematically,

[tex]Power=\frac{Work}{Time}[/tex]

Hence, The unit of work is Joule and Unit for power is Watt which is equal to Joule per second.

The rope will pull to the right side. This will happen because the force of the right team is higher (4332 N) than the team on the left (4251 N). And if they need it the extra force would be 81 to the right.

Answer:

She is measuring her speed

Explanation:

Speed is defined as the ratio between the distance covered divided by the time taken to cover that distance:

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

where

d is the distance covered

t is the time taken

Since Mary is measuring how far she can run in a given period of time, she is measuring the distance she can travel (d) in a given time (t), so she is measuring her speed.

Horizontal component of force is used to find out the work done

[tex]W = Fdcos\theta[/tex]

so we can say the work done as

[tex]W = (Fcos\theta)d[/tex]

so here the vertical component of force is not used to find out the work done

so here it would be

[tex]F_y = Fsin\theta[/tex]

[tex]F_y = 245sin55[/tex]

[tex]F_y = 200.7 N[/tex]

so 200.7 N is not used to find out work done

Answer:

4.9 meters

Explanation:

We know that an 11 lb bowling bowl was dropped.

So we can say that the initial speed of the bowling ball is zero ,

the time taken by the bag to free fall is given as  t = 1.0 s; and

the acceleration of free fall is given as  a = 9.8 m/s[tex]^2[/tex].

So we will use the following equation to find the distance after falling fo 1 sec:

[tex]d=v_i*t+\frac{1}{2} at^2[/tex]

Substituting the given values to get:

[tex]d=0+\frac{1}{2} * 9.8 * 1^2[/tex]

[tex]d=4.9[/tex]

Therefore, the bowling ball will cover a distance of 4.9 meters when released from the top of the building.

Answer:

B) The final acceleration will triple between the first and third trial.

Explanation:

From the relationship (acceleration) = (force) / (mass) it follows that the acceleration is directly proportional to the force applied. During the second experiment the acceleration will double (as force doubles), and during the third it will be tripled compared to the first.

Answer: 23 electrons.

Explanation: an atom have equal number of protons and electrons.

Filtration is the process we can use here as distillation is done mostly in liquids and we can use distillation here to seperate the substances from the soil.

Answer:

Filtration

Explanation:

Hi, to have in mind:

The filtration is a physical process used to separate two or more components due to their different size of particule (or unit).

The destilation is a chemical process used to separate two or more componets due to the difference between their boiling points (usually used with liquids).

Being that said, by filtration you can separate the leaves, acorns and twigs from the soil.

1. The magnitude of the magnetic field doubles

Explanation: the intensity of the magnetic field produced by a current-carrying wire is given by:

[tex]I=\frac{\mu_0 I}{2 \pi r}[/tex]

where [tex]\mu_0[/tex] is the vacuum permeability, I is the current in the wire, r is the distance from the wire.

As we see from the formula, the intensity of the magnetic field is directly proportional to the current: if the current increases from 5 A to 10 A, it means it doubles, so the magnetic field doubles as well.

2. The magnitude of the magnetic field halves

Explanation: the intensity of the magnetic field produced by a current-carrying wire is given by:

[tex]I=\frac{\mu_0 I}{2 \pi r}[/tex]

We see that the magnitude of the magnetic field is inversely proportional to the distance from the wire (r). In this case, the distance of the particle is changed from 10 cm to 20 cm, so it is doubled: therefore, the magnitude of the field will become half of the initial value.

3. The force reverses direction

Explanation: the force exerted on a charged particle in a magnetic field is:

[tex]F=qvB sin \theta[/tex]

where q is the charge, v is the speed of the particle, B is the magnetic field intensity and [tex]\theta[/tex] the angle between the direction of v and B. If the charge of the particle is switched from 2 µC to –2µC, the magnitude of the force does not change (because the absolute value of q does not change), however the charge q gets a negative sign (-), so the sign of the force changes and gets a negative sign too, so the force reverses direction.

(a) When the current increases from 5 A to 10 A, the strength of the magnetic field increases.

(b) When the distance  from the wire increases, the strength of the magnetic field decreases.

(c) When the sign of the charge changes and the magnitude is the same, the strength of the magnetic force will remain the same.

The magnetic field due to a distance from a wire is given as follows;

[tex]B = \frac{\mu_o I}{2\pi r}[/tex]

where;

Thus, when the current increases from 5 A to 10 A, the strength of the magnetic field increases.

Also, when the distance  from the wire increases, the strength of the magnetic field decreases.

The magnetic force on a charged particle moving in a magnetic field is given as;

F = qvB

where;

The magnetic force considers the magnitude of the charge, thus when the sign of the charge changes and the magnitude is the same, the strength of the magnetic force will remain the same.

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The answer is B.one plate slides beneath another due to gravitational pull.

Answer:

Its B

Explanation:

took the test 2020

Answer:

 Option B is the correct answer.

Explanation:

 We have expression for sound intensity level,

                  [tex]L=10log_{10}\frac{I}{I_0}[/tex], where I is the intensity.

Here new intensity is given by 4I.

So, increase in  sound intensity level

        [tex]\delta L=10log_{10}\frac{4I}{I_0}-10log_{10}\frac{I}{I_0}=10log_{10}\frac{4I}{I}=6dB[/tex]

So, option B is the correct answer.

The height of the cliff from which the ball was dropped from is 224.4m.

Given the data in the question;

To get the height of the Cliff, we use the Second Equation of Motion:

[tex]s = ut + \frac{1}{2}at^2[/tex]

Where s is the distance or height, [tex]u[/tex] is the initial velocity, t is the time and a is the acceleration. Since the ball was thrown down from a certain height (cliff), its is now under the influence of gravity. acceleration due to gravity; [tex]g = 9.8m/s^2[/tex]

Hence, the equation becomes

[tex]s = ut + \frac{1}{2}gt^2[/tex]

We substitute the given values into the equation

[tex]s = ( 8m/s\ *\ 6s) + (\frac{1}{2}\ *\ 9.8m/s^2\ *\ (6s)^2)\\\\ s = ( 48m ) + (4.9m/s^2\ *\ 36s^2)\\\\ s = ( 48m ) + (4176.4m)\\\\ s = 224.4m[/tex]

Therefore, the height of the cliff from which the ball was dropped from is 224.4m

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A spinning disk with 130 rev/min will make 33.5833 revolutions in 31 seconds.

Initial angular velocity,

wi = 2π. f

Where, f - frequency = 130 rev/min = 13/6 rev/s

Thus,

wi = 2π × 13/6

wi = 13π/3 rads/s

Final  angular velocity,

wf = 0 rads/s = wi + at

From acceleration,

a = -wi/t

Where,

a - acceleration

t - time = 31s

So,

t = -13π/3 × 1/31

t = -13π/93 rads/s²

From relation between Tangential velocity and Angular velocity,

wf² - wi² = 2a∅

Where, ∅ is the Tangential velocity

Thus,

-169π²/9 rads²/s² = 2 × -13π/93 rads/s² × ∅

∅ = 1209π/18 rads

Thus, the the number of rotations,

n = ∅/2π

n = (1209π/18)/(2π)

n = 1209/36

n  = ≈ 33.5833 revolutions.

Therefore, the disc make 33.5833 revolutions in 31 seconds.

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Answer: d

Explanation:

For an object to move in a uniform circular motion, only force that acts on it is the centripetal force which acts along the line joining the object and center of the circular path. The acceleration also acts in the direction of force. The centripetal acceleration acts along the radius of the circular motion path.

In the given horizontal circle, the direction of the acceleration of the object points towards d.

Answer:

D.

Explanation:

Because they have added another solution, it means that the mixture was not yet saturated, so the correct answer is unsaturated, D

Answer:  D) unsaturated

Explanation:

A) Saturated solution is defined as the solution in which no more solute particles can be dissolved in the solvent.

B) Semisaturated is defined as the solution in which half of the amount has been added and  another half has to be added for saturation.

C) Supersaturated solution is defined as the solution in which more amount of solute particles is present than the solvent particles.

D) Unsaturated solution is defined as the solution in which more solute particles can be dissolved in the solvent.

When oxygen reacts with sodium, the electrons move from the sodium atoms to the oxygen atoms which is denoted as option B.

This is referred to as electrovalent bonding and usually occurs between a metal and non metal.

The metal in this scenario is Sodium which loses electron to the non metal which is oxygen to become positively charged.

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g≈10 m/s²

F=G=mg=65*10=650 N

L=F*h=650*7=4550 J

P=L/t=>t=L/P=4550/300=15.16 s

The second statement is the correct choice.  Don't make me type it out.

Friction is the force that opposes motion and exists whenever two surfaces are in contact. It works to slow down or prevent motion, as seen when a book sliding across a table eventually stops.

The force that opposes the motion and can be found anytime two surfaces are in contact is known as friction. Friction is a resistance force that slows or prevents motion between two surfaces that are touching. For instance, if you slide a book across a table, it will eventually stop because of the frictional force between the book and the table's surface. It's also important to note that friction can come in several types, like static friction (friction that prevents an object from starting to move) and kinetic friction (friction that acts on moving objects).

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4 times the mass of Earth . . . multiplies Earth gravity by 4

1/2 of Earth's radius . . . multiplies Earth's gravity by 4

both changes . . . multiplies Earth gravity by (4 x 4) = 16

The acceleration of gravity on the surface of Planet-X is 16 TIMES that on the Earth's surface ... about 6.3 times what it is on Jupiter.

You could not walk around on Planet-X, and it's pretty likely that whatever contraption you landed in could not take off again.  You're stuck on Planet-X, living out the short remainder of your life just laying there like a heavy pancake and using all of your strength just trying to breathe.  It won't be pretty.

Answer:

a. molecules become lighter when heated

Reason:

Hot air balloons rise because the heated air inside the balloon is less dense than the cool air outside. This difference in density creates a buoyant force that causes the balloon to rise. The increase in temperature causes the molecules in the gas to move faster and spread apart, further decreasing the density and increasing the buoyancy.

Hot air balloons rise because the molecules in the heated air are less dense compared to the surrounding cool air. This decrease in density creates a buoyant force that causes the balloon to rise. As the temperature of the gas inside the balloon increases, the molecules move faster and farther apart, resulting in a decrease in density and an increase in buoyancy. The expansion of gases and the rapid motion of atoms and molecules in a gas also contribute to the balloon's ability to rise.

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1. Sodium metal reacts vigorously with water to produce hydrogen gas.

Chemical. A chemical property can only be observed by changing the chemical identity of a substance.

2. Steel is attracted to magnets.

Physical. A physical property is is an aspect of matter that can be observed or measured without changing its chemical composition.

Answer:

chemical & physical

Explanation:

The box has the square shape and thus its length, width and height all will be equal. The volume of a square  is the cube of its side where as sides are equal. Thus the length, width and height of the box is 3.17 m.

A square is geometry having all sided equal. Thus, its, length, breadth and height will be equal. Let a be the side of the square. Then the surface area of the square will be a².

The volume of a square is equal to the cube of the length of side. Thus if a being the side length, volume of the square box will be a³. Similarly volume of any geometry is the product of its length, breadth and height and it is expressed in m³ or cm³.

Given that the volume of the square box is 32 m³. Thus length of its side is calculated as:

a³ = 32

 a = ∛32

    = 3.17 m.

Hence, the dimension of the box is 3.17 m side with surface area  (3.17)² =10.09 m².

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Final answer:

The dimensions of the box with the least possible surface area are x = 2 meters (side length of the square bottom) and h = 8 meters (height).

Explanation:

To find the dimensions of the box with the least possible surface area, we need to optimize the proportions while keeping the volume constant. Let's denote the side length of the square bottom as x and the height of the box as h. The volume of the box is V = x²h, and we are given that V = 32 cubic meters. To minimize the surface area, we need to minimize the sum of the areas of all the sides.

The surface area of the bottom is x², the surface area of each of the vertical sides is 4xh (there are four sides), and the surface area of the top is also x². Therefore, the total surface area A in terms of x and h is A = x² + 4xh + x² = 2x² + 4xh.

To find the dimensions that minimize the surface area, we can use the volume equation V = 32 and solve for h in terms of x: h = 32/x². Substituting this expression for h into the surface area equation gives A = 2x² + 4x(32/x²) = 2x² + 128/x.

To minimize A, we can take the derivative of A with respect to x, set it equal to zero, and solve for x. The derivative of A with respect to x is dA/dx = 4x - 128/x². Setting this equal to zero gives 4x - 128/x² = 0. Multiplying through by x² gives 4x³ - 128 = 0.

Simplifying further, we have 4x³ = 128, so x³ = 32. Taking the cube root gives x = ³∛32 = 2 meters.

Finally, we can substitute this value of x back into the expression for h to find h = 32/(2²) = 8 meters. Therefore, the dimensions of the box with the least possible surface area are x = 2 meters (side length of the square bottom) and h = 8 meters (height).

Answer:

B. Spring

Explanation:

The waters of a lake will be the most layered in the spring because of the melting of the ice (which is just frozen water) and the direct heat going into the lake causing the warm water to rise up and the colder water to move further down, which creates even more layers.