the velocity of a diver just before hitting the water is -10.1 m/s, where the minus sign indicates that her motion is directly downward. what is her displacement during the last 1.20 s of the dive?

A. Hypothesis (What do you believe will happen?) People who increased their caloric intake by 1000 calories per day are more likely to develop hypertension (high blood pressure).

Hypothesis is a process of generating testable predictions about a certain phenomenon. It is an educated guess or explanation of a certain phenomenon, based on available facts and evidence. It is the starting point for further investigation and helps to determine the outcome of a scientific experiment. Hypothesis helps to develop a framework of understanding and can be used to create further predictions. It is an essential step in the scientific method, as it helps to structure an experiment and provide a basis for further evaluation.

B. Experiment (Procedures that lead to a discovery or test a hypothesis.) An experimental group of 20 subjects will consume an extra 1000 calories per day from fast food, in addition to their normal daily caloric intake. A control group of 20 subjects will not consume an extra 1000 calories from fast food and will continue with their normal diet. The blood pressure of each subject in both groups will be recorded once per week for eight weeks.

C. Results (The outcome of the experiment.) After eight weeks, 70% of subjects in the experimental group had developed hypertension. In the control group, only 5% of subjects developed hypertension. The hypothesis was supported by the data; the increased intake of calories in the experimental group increased the likelihood of developing hypertension.

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Answer:

B

Explanation:

Answer:

3386.23 Km

Explanation:

Without any wind interference the speed of the plane, it flies at 2.42 x 102 m/s or 242 m/s

The magnitude of the velocity of the air = 40.7-m/s

The time taken, for the plane to fly due west, tw = distance, x ÷ (speed of the plane without wind interference, up - the magnitude of the velocity of the air, ua).......... (equation 1)

The time taken, for the plane to fly due east, te = distance, x ÷ (speed of the plane without wind interference, up + the magnitude of the velocity of the air, ua).......... (equation 2)

To calculate the total time, t, the plane can fly to cover east and west distances, we add equation 1 and 2 together

t = (x ÷ (up - ua)) + (x ÷ (up + ua))

Making distance x, the subject of the formula we have:

x = t ( up²- ua²) ÷ 2up

note t = 8.0 hours which is (8 x 60 x 60) seconds = 28,800‬

So, x = 28,800‬ ((242 m/s)² - (40.7-m/s)²)÷ 2(242 m/s)

x= 1,638,936,288‬ ÷ 484

= 3386.23 Km

In the event of an accident or a car crash, road safety barriers and fences prevent automobiles from running off the road.

Newton's Three Laws of Physics can help explain what these safety barriers are and how they help to save lives during car accidents :

I.  Unless acted upon by an imbalanced force, an object at rest will remain at rest, and an object at constant velocity will remain at constant velocity.

II.  If an imbalanced force occurs, a mass will experience acceleration proportional to its magnitude.

III.  When you apply a force to an object, you will feel a force that is equal    in magnitude but opposite in direction.

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To determine whether the image of the pencil is on the surface of the mirror or behind the mirror, we need to understand the concept of reflection. When light rays from an object (in this case, the pencil) hit a mirror, they bounce off and form an image. This image can either be virtual or real.

In the case of a mirror, the image formed is virtual, meaning it cannot be projected onto a screen. When you look at the image in the mirror, you are actually seeing the light rays that have bounced off the mirror and reached your eyes.
Now, let's address the two assertions. The statement that the image is on the surface of the mirror is not accurate. The image is not physically present on the mirror's surface. Instead, it appears to be located behind the mirror.
When you see the image in the mirror, it appears to be at the same distance behind the mirror as the object is in front of it. This is due to the nature of the reflection process.
Therefore, the correct assertion is that the image of the pencil is behind the mirror, not on its surface.

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If an object is floating in equilibrium on the surface of a liquid and is then removed and placed in another container filled with a denser liquid, we would observe that the object would sink in the denser liquid.

This is because the buoyant force acting on an object is equal to the weight of the displaced fluid. When the object is placed in a denser liquid, it will displace less fluid compared to the previous liquid, resulting in a lower buoyant force. This decrease in buoyant force will no longer be able to counteract the weight of the object, causing it to sink.

The denser liquid has a higher mass per unit volume, which means that it will exert a stronger force on the object, causing it to sink. This concept is important in understanding why some objects float while others sink, as the buoyant force and weight of the object must be in equilibrium for it to float. If the object is denser than the liquid, it will sink, but if it is less dense, it will float.

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The velocity of the object s calculated as 22.1 m/s.

Given that we can write that;

v^2 = u^2 + 2gh

Now u = 0 m/s because the object was dropped from a height

v^2 = 2gh

v = √2 * 9.8 * 25

v = 22.1 m/s

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Answer:

d

Explanation:

Answer:

Velocity (v) is a vector quantity that measures displacement (or change in position, Δs) over the change in time (Δt), represented by the equation v = Δs/Δt. Speed (or rate, r) is a scalar quantity that measures the distance traveled (d) over the change in time (Δt), represented by the equation r = d/Δt.

Explanation:

The formula for speed is speed = distance ÷ time.

Answer:

the power developed by the automobile is 7,764.57 W.

Explanation:

Given;

mass of the automobile, m = 2500 kg

initial power developed by the automobile, P₁ = 30 kW = 30,000 W

initial speed of the automobile, v₁ = 90 km/h = 25 m/s

inclination of the hill, θ = 15⁰

second speed of the automobile, v₂ = v₁Sinθ

The power developed by the automobile is calculated as;

P = Fv

\(F = \frac{P_1}{V_1} = \frac{P_2}{V_2} \\\\P_2 = \frac{P_1V_2}{V_1} \\\\P_2 = \frac{30,000 \ W \ \times 25Sin(15^0)}{25} \\\\P_2 = 30,000 \ \times sin(15^0)\\\\P_2 = 7,764.57 \ W\\\\\)

Therefore, the power developed by the automobile is 7,764.57 W.

The impedance of the given AC circuit containing resistor and inductor parallel to each other is 55.71 ohms.

The given parameters;

The inductive reactance is calculated as follows;

\(\omega _l = 2\pi fl\\\\\omega _l = 2\times 3.142 \times 2,000\times 10\times 10^{-3} = 125.68 \ ohms\)

The impedance is the total opposition to the flow of current in the AC circuit and it is calculated as follows;

\(Z _{total} = \frac{1}{\frac{1}{Z_l} + \frac{1}{Z_R} } \\\\Z _{total} = \frac{1}{\frac{1}{125.68} + \frac{1}{100} }\\\\Z _{total} = 55.71 \ ohms\)

Thus, the impedance of the given circuit is 55.71 ohms.

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Answer:

Tendon

Explanation:

Tendons are a type of connective tissue that attach muscle to bone. Hope this helps! :)

The statement is True. Ampère's law is indeed often written as ∮B(r)⋅dl = μ₀Iencl.

Ampère's law states that the magnetic field B around a closed loop is proportional to the net current Iencl passing through the loop. In the equation, ∮B(r)⋅dl represents the line integral of the magnetic field B around the closed loop, μ₀ is the permeability of free space (4π x 10^(-7) Tm/A), and Iencl is the net current enclosed by the loop.

The law is used to determine the magnetic field generated by currents in conductors and is particularly useful in calculating the magnetic field for cases with high symmetry.

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Before we solve this, we should know this fact:

According to Newton's Law of Gravitation, the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The force acts along the line joining the centres of the two objects. It can be shown by this:

\(F ∝ \frac{Mm}{ {d}^{2} } \)

Now, let us check all the options.

A. As we move to higher altitudes, the force of gravity on us decreases.

This statement is true.

The force of gravity is inversely proportional to the square of distance from the centre of the earth. If, we go up the surface of the earth, the distance from the centre of the earth increases and hence the value of force of gravity decrease. So, force of gravity decreases with altitude.

B. As we move to higher altitudes, the force of gravity on us increases.

This statement is false.

We have already got the result in option A. that the force of gravity decreases with altitude. It never increases with altitude.

C. As we gain mass, the force of gravity on us decreases.

This statement is false.

The force of gravity is directly proportional to the product of the masses. So, if increase our mass, then the force of gravity will also increase and if we decrease our mass, then the force of gravity decreases.

D. As we gain mass, the force of gravity on us increases.

This statement is true.

As mentioned earlier in option C., the force of gravity is directly proportional to the product of the masses of the earth and another object. So, as we gain mass, the force of gravity on us increases.

E. As we move faster, the force of gravity on us increases.

This statement is true.

Here, we have to consider a different formula. According to Newton's Second Law,

F = ma, where F is the force, m is the mass and a is the acceleration.

In other words,

F ∝ a, i.e., force is directly proportional to acceleration.

We know, acceleration is the rate of change of velocity of an body within a time period.

So, if speed is increased, then acceleration will also be greater, which results in the increase of force. So, as we move faster, the force of gravity on us increases.

Answers:

A: As we move to higher altitudes, the force of gravity on us decreases.

D: As we gain mass, the force of gravity on us increases.

E: As we move faster, the force of gravity on us increases.

Hope you could understand.

If you have any query, feel free to ask.

The required donor impurity concentration and electron mobility for a conductivity of 10 (-cm)⁻¹ are both 10 cm⁻³.

In sοlid-state physics, the electrοn mοbility characterises hοw quickly an electrοn can mοve thrοugh a metal οr semicοnductοr when pulled by an electric field. There is an analοgοus quantity fοr hοles, called hοle mοbility. The term carrier mοbility refers in general tο bοth electrοn and hοle mοbility.

To determine the required donor impurity concentration and electron mobility for a given conductivity in an n-type silicon sample, we can use the following relations:

1. Donor Impurity Concentration (Nd):

Nd = (σn * q * μn) / (|e|)

2. Electron Mobility (μn):

μn = σn / (q * Nd)

Where:

Given:

First, let's calculate the donor impurity concentration (Nd):

Nd = (σn * q * μn) / (|e|)

To calculate the electron mobility (μn), we need to know the value of Nd.

So, we'll calculate Nd using the given values, and then find μn:

Nd = (10 * 1.6 x \(10^{-19\) * μn) / (1.6 x \(10^{-19\))

Nd = μn

Hence, the donor impurity concentration (Nd) and the electron mobility (μn) will have the same value.

Therefore, the required donor impurity concentration and electron mobility for a conductivity of 10 (-cm)⁻¹ are both 10 cm⁻³.

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A beam of blue light causes photoelectrons to be emitted from a photoemissive surface. An increase in the intensity of the blue light will cause an increase in the number of photoelectrons emitted. Therefore, an increase in the intensity of blue light will cause an increase in the light intensity.

What is light? Light is a type of electromagnetic radiation that travels in waves at a velocity of 299,792 kilometers per second (km/s) in a vacuum. It is a form of energy and, like all forms of energy, can be transferred. Light, like other electromagnetic waves, has both electric and magnetic fields that oscillate perpendicularly to one another at right angles.Light has a very important property, which is its intensity. The amount of light that passes through a given area or space per unit time is known as light intensity. It is the amount of light energy that falls on a unit area in a given time. The energy of light, like all energy, can be described in terms of photons.

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The value of force is 1.7 × 10⁻³ N, with the direction opposite to that of the bat's motion.

When an object collides with another object, they exchange energy. For example, a baseball and bat collision or a car collision. When two objects collide, the force of the collision has to be equal on both sides of the collision according to Newton's Third Law. So, to find the value of force, we will apply the equation:

F = ΔP / ΔT

where F is the force, ΔP is the change in momentum, and ΔT is the time of collision. The equation represents the impulse momentum theorem.

Now, let's apply the given values to the above equation.

Final momentum (p2) = mass × final velocity (v2)

p2 = 0.15 kg × (-50 m/s)

p2 = -7.5 kg.m/s

Initial momentum (p1) = mass × initial velocity (v1)

p1 = 0.15 kg × (40 m/s)

p1 = 6 kg.m/s

Change in momentum (ΔP) = p2 - p1

ΔP = -7.5 kg.m/s - 6 kg.m/s

ΔP = -13.5 kg.m/s

Time of collision (ΔT) = 8.0 × 10³ s

Now, putting the values of ΔP and ΔT in the equation of impulse momentum theorem, we get:

F = ΔP / ΔT

F = -13.5 kg.m/s ÷ 8.0 × 10³ s

F = -1.7 × 10⁻³ N

Thus, the value of force is 1.7 × 10⁻³ N, with the direction opposite to that of the bat's motion.

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The barometric pressure in centimeters of water (cmH₂O) if a mercury barometer reads 803 mmHg and the density of mercury is 13.5 g/mL and the density of water is 1.00 g/mL is 1033.25 cmH₂O.

1. Convert 803 mmHg to cmH₂O using the conversion factor 1 mmHg = 1.36 cmH₂O.

803 mmHg × 1.36 cmH₂O/mmHg = 1092.08 cmH₂O.

2. Determine the pressure due to the mercury column using the density of mercury and the height of the mercury column. The height of the mercury column is the same as the pressure reading in mmHg.

Pressure = density × gravity × height. 13.5 g/mL × 9.81 m/s² × (803 mmHg ÷ 760 mmHg/atm) × (1 atm/101325 Pa) = 101.47 kPa.

3. Determine the pressure due to the air above the mercury column. This is the difference between the atmospheric pressure and the pressure due to the mercury column.

Atmospheric pressure = 1 atm = 101.325 kPa.

Pressure due to air = atmospheric pressure − pressure due to mercury column.

Pressure due to air = 101.325 kPa − 101.47 kPa = −0.145 kPa.

4. Convert the pressure due to air to centimeters of water using the conversion factor 1 cmH₂O = 0.098 kPa. −0.145 kPa × (100 cmH2O/0.098 kPa) = −148.47 cmH2O.5.

Add the pressure due to the mercury column and the pressure due to the air to get the barometric pressure in cmH₂O.

Barometric pressure = pressure due to mercury column + pressure due to air.

Barometric pressure = 1092.08 cmH₂O + (−148.47 cmH₂O) = 943.61 cmH₂O.

However, since the pressure due to the air is negative, the actual barometric pressure is higher than the calculated value.

The correct answer is 1092.08 cmH₂O − 148.47 cmH₂O = 943.61 cmH₂O + 1090.86 cmH₂O = 1033.25 cmH₂O.

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No.of primary turns/no.of secondary equal to current in primary /current in secondary therefore 200/120=3.50/C.in secondary =2.1A

Speed will it strike the positive plate 74.736*10^6 m/s

r = distance = 3.7 mm

a) E = electric field between plates =

E =  38*10^-6  / 8.85*10^-12

   = 4.293*10^6 N/C

from E = -dV / dr

dV = potential difference .  take magnitude:

dV = E*dr

   = 4.293*106*3.7*10-3

   = 15.887 *103V

b) from F ( force) = q*E

also F = ma

so                 ma = qE

a( acceleration) = qE/ m

q = charge on electron, m= mass

a  = 1.6*10^-19*4.293*10^6 / 9.1*10^-31

a = 7.548*1017 m/s2

u = initial velocity = 0 m/s ( at rest)

V = final velocity= ?,           S = distance = r = 3.7 mm

v^2 = u^2+2as

putting values we get

Speed will it strike the positive plate 74.736*10^6 m/s

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Answer:

323.4N

Explanation:

Given parameters:

Mass of the box = 33kg

Unknown:

Normal force on the body  = ?

Solution:

The normal force of a body is the vertical force the body exerts on another body.

It is expressed as;

        Normal force  = mass x acceleration due to gravity

Acceleration due to gravity  = 9.8m/s²

Normal force  = 33 x 9.8  = 323.4N

Tarzan weighs 73 kg. From a 26.1 m vine, he swings. Tarzan is travelling at 3.65 m/s when he is at his lowest point in his swing. The vine is under 2635.3 kg-m/s^2 of tension at the swing's lowest point.

The force communicated through a rope, string, or wire when two opposing forces draw on it is known as tension. The tension force pulls energy equally on the bodies at the ends and is applied along the entire length of the wire. Every physical object in contact with another one applies some force to that object. For items that are hung, the tension is equal to the gravitational acceleration times the mass of the object.

Here m=73kg

acc (a) = 26.1 m

g=10

d= 3.65 m/s

Tension t = mg + ma.

Tension t = m(g + a).

t = m(g + a)

t= 73(10+26.1)

t= 73(36.1)

t= 2635.3 kg-m/s^2

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The efficiency of the engine is 16%.

The efficiency of the engine is given by,

η = W/Q

η = (W₁ + W₂ + W₃ + W₄)/(Q₁ + Q₂ + Q₃ + Q₄)

Since, the steps 2 and 4 are held at constant volume, the work done in these steps will be zero. Also, the heat enters into the system only during the steps 1 and 4.

So, the efficiency,

η = (W₁ + W₃)/(Q₁ + Q₄)

In step 1

The work done in isothermal expansion,

W₁ = nRT ln(V₂/V₁)

During isothermal expansion, there is no change in internal energy. So, the heat energy,

Q₁ = W₁ = nRT ln(V₂/V₁)

In step 3

Work done in isothermal compression,

W₃ = nRT₂ ln(V₄/V₃)

In step 4

The heat entering into the system,

Q₄ = CvΔT = Cv(T₁ - T₂)

Therefore, efficiency,

η = [nRT₁ ln(1.88) + nRT₂ ln(1/1.88)]/[nRT₁ ln(1.88) + Cv(T₁ - T₂)]

η = (280 - 151)/[280 + (21/8.314 ln(1.88)) (280 - 151)

η = 0.16

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Although most astronomers assume dark matter really exists, there is at least one other possible explanation for the phenomena attributed to dark matter. What is it?

It's possible that our understanding of how gravity behaves on galaxy-scales is inaccurate or lacking in some way.

We surmise that dark matter exists based on its gravitational pull on visible matter. In order to rule out the idea that our comprehension of gravity is leading us to incorrectly infer the presence of dark matter, the majority of scientists believe it to be extremely unlikely that there is a problem with our knowledge of gravity. As long as it is too faint for us to perceive beyond the halo of our galaxy, astronomers regard dark matter to be "dark." If a human were to be hurled into the halo of our galaxy, they might end up being dark matter. An estimated 85% of the universe's mass is assumed to be made up of dark matter, a hypothetical type of stuff. Dark matter is so-called because it doesn't seem to interact with the electromagnetic field, which means it doesn't emit electromagnetic radiation like light or absorb electromagnetic radiation like it does. As a result, it is hard to detect. Numerous astrophysical observations support the existence of dark matter, including gravitational effects that cannot be described by the gravity theories currently in use without the presence of more matter than can be observed. Because of this, the majority of scientists believe that dark matter is prevalent in the universe and has greatly influenced its structure and evolution.

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Explanation:

Given data

distance = 5km

time taken to travel to school= 30 min

1. the total distance traveled is

from home to school+ school to home+ home back to school

5km+5km+5km= 15 km

2. Determine the students average speed

average speed is the total distance divided by the total time taken

= (5+5+5)/(30+30+27)

= 15/87 km/min

3  What is the student total displacement

the displacement tells how far a place is  hence the displacement is 5km (i.e the school is 5km from his home)

4. Determine the students average velocity

a. speed home to school

      v= 5/30= 0.166 km/min

b. school back home

      v= 5/30= 0.166 km/min

c. speed home to school

      v= 5/27= 0.185 km/min

Average velocity =  (0.185 + 0.166 + 0.166)/3= 0.517/3= 0.17 km/min

After watching the Ted Talk, there were still a few questions that I had about supermassive black holes. Firstly, I wanted to know more about the event horizon and what it exactly entails. Although the speaker briefly touched upon this subject, I would have appreciated a more in-depth explanation. Additionally, I would have liked to know more about the role of supermassive black holes in the universe.

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Rotation curves of galaxies imply the existence of dark matter because they show unexpected and anomalous behavior in the distribution of mass within galaxies.

The rotation curve of a galaxy describes the rotational velocity of stars or gas clouds at various distances from the galactic center. According to Newtonian physics, the rotational velocity should decrease with increasing distance from the center, as the gravitational pull weakens. However, observations have revealed that the rotational velocities remain constant or even increase with distance from the center, indicating the presence of additional mass beyond what is accounted for by visible matter. This discrepancy between the predicted and observed rotational velocities suggests the existence of unseen matter, commonly referred to as dark matter.

Dark matter does not emit or interact with light, making it invisible and difficult to detect directly. However, its gravitational effects can be observed through its influence on the motion of visible matter. The presence of dark matter provides the additional gravitational pull required to explain the observed high rotational velocities of stars and gas clouds in galaxies. Various astrophysical and cosmological studies, such as gravitational lensing and the cosmic microwave background radiation, further support the existence of dark matter.

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Answer:

The answer is D.

Explanation: