Science questions!! Please help!!
Post Assessment on Investigating the Immune System
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Answer:

Explanation:

Answer:

B

Explanation:

Atoms are made by electrons, neutrons and protons

Answer:

A. there are distinct kinds of atoms

Explanation:

According to Dalton's atomic theory, the atom is indivisible. Thus, we know that B is incorrect. Additionally, C can't be correct because when Dalton was alive, the nucleus (the small, dense center) hadn't yet been discovered. Finally, D can't be correct either since Bohr's discoveries about electron orbits hadn't yet been made. Knowing that, it must be A!

Also, I just did the quiz, and it was A. Dalton believed that there are distinct kinds of atoms!

Answer:

[tex]56.5\ \text{s}[/tex]

[tex]21.13\ \text{m/s}[/tex]

Explanation:

v = Final velocity

u = Initial velocity

a = Acceleration

t = Time

s = Displacement

Here the kinematic equations of motion are used

[tex]v=u+at\\\Rightarrow t=\dfrac{v-u}{a}\\\Rightarrow t=\dfrac{25-0}{2}\\\Rightarrow t=12.5\ \text{s}[/tex]

Time the car is at constant velocity is 39 s

Time the car is decelerating is 5 s

Total time the car is in motion is [tex]12.5+39+5=56.5\ \text{s}[/tex]

Distance traveled

[tex]v^2-u^2=2as\\\Rightarrow s=\dfrac{v^2-u^2}{2a}\\\Rightarrow s=\dfrac{25^2-0}{2\times 2}\\\Rightarrow s=156.25\ \text{m}[/tex]

[tex]s=vt\\\Rightarrow s=25\times 39\\\Rightarrow s=975\ \text{m}[/tex]

[tex]v=u+at\\\Rightarrow a=\dfrac{v-u}{t}\\\Rightarrow a=\dfrac{0-25}{5}\\\Rightarrow a=-5\ \text{m/s}^2[/tex]

[tex]s=\dfrac{v^2-u^2}{2a}\\\Rightarrow s=\dfrac{0-25^2}{2\times -5}\\\Rightarrow s=62.5\ \text{m}[/tex]

The total displacement of the car is [tex]156.25+975+62.5=1193.75\ \text{m}[/tex]

Average velocity is given by

[tex]\dfrac{\text{Total displacement}}{\text{Total time}}=\dfrac{1193.75}{56.5}=21.13\ \text{m/s}[/tex]

The average velocity of the car is [tex]21.13\ \text{m/s}[/tex].

Answer:

A. like charges repel, unlike charges, attract

Explanation:

A charge can be positive or negative.

Like charges, example positive and positive or negative and negative, repel each other, while unlike charges, example positive and negative attract each other.

From the given options, the correct option is A.

A. like charges repel, unlike charges, attract

The statement which is true for the interaction of charges is the like charges repel, unlike charges, attract (A).

When the two charges or the charged bodies interact each other, the force of attraction or repulsion acts between them. This force of attraction or repulsion can be find out using the coulombs' law.

This force of attraction or repulsion is identified by the sign of the particular charge. According to the property of interacting charges-

Thus, the statement which is true for the interaction of charges is the like charges repel, unlike charges, attract (A).

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Answer:

The answer is C.

Explanation:

If you have ever tried doing so, hair stick to the ballon. Opposites attract as well, so the answer is C.

Answer:

 θ = 35.7º

Explanation:

For this exercise we must use the law of Malus

          I = I₀ cos² θ

where the angle is between the two polarizers.

When the unpolarized light from the sun reaches the first polarizer, only the light polarized in the direction manages to be transmitted, which is why

          I₁ = I₀ /2

this light reaches the second polarizer

           I₂ = I₁ cos² θ

           I₂ = I₀/2    cos² θ

           cos² θ = 2 I₂ / Io

indicate that the transmitted light is 33% = 0.33 I₀

          cos² θ = 2 0.33

          cos θ = √0.66

          θ = cos⁻¹ 0.8124

          θ = 35.7º

platinum is used because it is more stable, provides accurate results and has a broad temperature range.

Answer:

The excretory system is a close partner with both the circulatory and endocrine system. The circulatory system connection is obvious. Blood that circulates through the body passes through one of the two kidneys. Urea, uric acid, and water are removed from the blood and most of the water is put back into the system.

Explanation:

Limiting factors are resources or other factors in the environment that can lower the population growth rate. Competition for resources like food and space cause the growth rate to stop increasing, so the population levels off. This flat upper line on a growth curve is the carrying capacity.

Answer:

they can eat all of the food and kill off the population

Explanation:

if the competition eats all of the food there's no food for the population and they will die off.

Answer:

The wavelength will be "1.182 μm".

Explanation:

The given values are:

Wavelength

[tex]\lambda=591 \ nm[/tex]

or,

  [tex]=591\times 10^-9 \ m[/tex]

Distance,

[tex]d = 3.00 m[/tex]

[tex]n = 1[/tex]

Distance of fringe from center,

[tex]y = 4.84 \ mm[/tex]

We have to find the wavelength of first order dark fringe,

[tex]\lambda = ?[/tex]

As we know,

⇒ [tex]y_{bright} =\frac{1\times \lambda\times L}{d}[/tex]

On putting the given values in the formula, we get

   [tex]0.00484=\frac{1\times (591\times 10^{-9})\times 3}{d}[/tex]          

On applying the cross multiplication, we get

   [tex]\lambda = \frac{0.00484\times 000036632}{0.5\times 3}[/tex]

      [tex]=1182\times 10^{-9}[/tex]

or,

      [tex]=1.182 \ \mu m[/tex]    

Answer:

the percentage of heat lost by the window is 93.18%

Explanation:

Given the data in the question;

Area of glass [tex]A_{glass[/tex] = 0.10 m²

Thickness of glass [tex]t_{glass[/tex] = 8 mm = 0.008 m

Area of Styrofoam [tex]A_{styrofoam[/tex] = 11 m²

Thickness of Styrofoam [tex]t_{styrofoam[/tex] = 0.15 m

we know that;

Thermal conductivity of glass [tex]k_{glass[/tex] =  0.80 J/smC°

Thermal conductivity of Styrofoam  [tex]k_{styrofoam[/tex] =  0.010 J/smC°

Now, temperature difference between outside and inside the walls and window is ΔT

So, In time t, heat lost due to conduction in the window will be;

[tex]Q_{glass[/tex] = [[tex]k_{glass[/tex] × [tex]A_{glass[/tex]  × ΔTt] / [tex]t_{glass[/tex]

we substitute

[tex]Q_{glass[/tex] = [ 0.80 × 0.10 × (ΔT)t] / 0.008

[tex]Q_{glass[/tex] = [ 0.80 × 0.10 × (ΔT)t] / 0.008  

[tex]Q_{glass[/tex] = 10(ΔT)t J

Also, the heat lost due to conduction in the wall be;

[tex]Q_{styrofoam[/tex] =  [[tex]k_{styrofoam[/tex] × [tex]A_{styrofoam[/tex] × ΔTt] / [tex]t_{styrofoam[/tex]

we substitute

[tex]Q_{styrofoam[/tex] =  [ 0.010 × 11 × ΔTt] / 0.15

[tex]Q_{styrofoam[/tex] =  0.7333(ΔT)t J

Now, Net heat lost in the wall and window is;

Q = [tex]Q_{glass[/tex] + [tex]Q_{styrofoam[/tex]

Q = 10(ΔT)t J + 0.7333(ΔT)t J

Q = 10.7333(ΔT)t J

So, the percentage of heat lost by the windows will be;

% of heat lost = [tex]Q_{glass[/tex] / Q

= 10(ΔT)t J / 10.7333(ΔT)t J

= 0.93167

= ( 0.93167 × 100 )%

= 93.18%

Therefore, the percentage of heat lost by the window is 93.18%

Answer:

9.6 km/h

Explanation:

20 minutes=1/3 minute.

The speed of the bicycle: 3.2:1/3=9.6 km/h.

Answer: 9.6 km/h

The maximum compression in the spring is 0.06883 meters.

Given to us,

mass of bullet, [tex]m= 16.2\ grams[/tex]

velocity of bullet, [tex]v= 850\ meter/second[/tex]

mass of the block, [tex]m_2= 40\ kilograms[/tex]

velocity of block, [tex]v_2= 0\ meter/second[/tex]

spring constant, [tex]k = 1000\ Newton/meter[/tex]

Combined mass after collision,

[tex]\begin{aligned}M&= m_1+m_2\\&= 40.0162\ Kilograms\end{aligned}[/tex]

Using the momentum conservation equation, to find out final velocity of the system(bullet and block combined)

[tex]m_1v_1+m_2v_2= MV\\[/tex]

[tex]0.0162\times 850+40\times 0 = 40.0162\times V\\V= 0.3441 meter/sec[/tex]

Now using the Conservation of Energy (Kinetic energy of the system will be equal to potential energy in the spring), to find out the displacement of the spring [tex](x)[/tex]

[tex]\frac{1}{2}kx^2 = \frac{1}{2}MV^2\\\\\frac{1}{2}\times 1000\times x^2= \frac{1}{2} \times40.0162\times0.3441^2\\\\x^2= 0.004738\\\\x= 0.06883\ meters[/tex]

Hence, the maximum compression in the spring is 0.06883 meters.

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Answer:

Im so so sorry but I do now know how to do this

Explanation:

Answer:

Hi how are you doing today Jasmine

Answer:

The answer is B

Explanation:

I did the USA test prep

Answer:

Isotopic dating of meteor fragments

Explanation:

Earth is so old that its age can only be determined using isotopic dating. The oldest measurement of Earth's age was determined using isotopic dating of meteor fragments.

Answer: Isotopic dating of meteor fragments

Explanation:

102 m

Explanation:

The time 0.6 sec is the time it took for the sound to travel from the bat to the moth and back. So it took 0.3 sec for the sound to reach the moth. From the definition of speed, the distance of the moth d to the bat is given by

v = d/t ---> d = vt = (340 m/s)(0.3 sec) = 102 m

This question involves the concepts of kinetic energy, potential energy, and the law of conservation of energy.

The watermelon is "1.02 m" above the ground.

The total energy of the watermelon can be found by its potential energy at the highest point:

Total Energy = mgh

where,

Therefore,

Total Energy = (118 kg)(9.81 m/s²)(5 m)

Total Energy = 5787.9 J

Now, according to the law of conservation of energy, at the given point:

Total Energy = Kinetic Energy + Potential Energy

5787.9 J = 4610 J + mgh'

[tex]h'=\frac{5787.9\ J-4610\ J}{(118\ kg)(9.81\ m/s^2)}[/tex]

h' = 1.02 m

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Combined energy of the two sleds will be conserved when they collides.

Energy is nothing but the ability to do work. there are different energies in different form which are thermal energy, mechanical energy, electric energy and sound energy etc.

According to first law of thermodynamic, Energy neither be created nor be destroyed. it can only be transferred from one form into another form. Energy is expressed in joule (J). its dimensions are [M¹ L² T⁻²].

Energy is conserved throughout the motion,

according to conservation law of energy, initial energy is equal to final energy.

When two sleds coming in opposite direction, it is having mass as well as velocity. hence it has kinetic energy, when they get collide with each other some of total energy gets converted into sound energy as collision cause sound(boom). some of the energy will use to break the material which made the sled and remaining energy will convert in kinetic energy of broken sleds it can be moved in opposite direction or in same direction depending initial energies.

in this collision combined kinetic energy can be converted into sound energy, mechanical energy and again kinetic energy but totally energy is conserved.

Hence combined energy will be conserved.

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Answer: a different one is a.b.c

Explanation: still for ape.x

The correct order to determine the age of the an object using carbon-14 is C, A, B. Thus, option D is correct.

The half-life time is defined as the time taken by the radioactive element to reduce one half of its initial value. It is denoted by t(1/2).

To measure the age of an object, a radioactive isotope called carbon-14 is used. The half-life of carbon-14 is 5,730 years. All the objects in the universe consumes carbon  in their lifetime and hence, carbon-14 is used to measure the age of the objects.

The process of determining the age of objects using carbon-14 is called Radiocarbon dating. All living organisms consume carbon in means of food and from atmosphere and when the plant and animals dies, the radioactive carbon atoms start decaying.

When it starts decaying, by using Carbon-14 the age of an object is calculated. The age is estimated by measuring the amount of carbon-14 present in the sample and comparing this carbon with the reference Carbon-14 isotope.

The amount of carbon in  preserved plants is identified by:

f(t) = 10e {₋ct}  

t = time in years when the plant dies( t= 0)

c = the amount of carbon-14 remaining in preserved plants.

The steps include to find the age of an object is :

1. Use the number of half-lives that have passed to determine the age of the object.

2. Use the half-life of carbon-14 to determine the number of half-lives that have passed.

3.Measure the ratio of parent nuclei to daughter nuclei.

Hence, from these steps the age of an object is determined. Therefore the correct solution is D) C, A, B.

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If ' c ' is the speed of light, then the formula for it is . . .

c = 299,792,458 meters per second

Answer:

3M/S

Explanation:

Answer:

Ellipse

Explanation:

Most comets have an elliptical path of orbit.

Answer: The shape of the orbit for most comets is: ellipse

Answer:

D. 2,1,2,1 ​

Explanation:

The equation of the reaction is; 2AgNO3 + BeCl2 + ---------》2AgCl + Be(NO3)2

The rule applied in balancing chemical reaction equation is that the number of atoms of each element on the reactants side must be the same as the number of atoms of the same element on the products sides.

If this rule is properly applied to the reaction between silver nitrate and beryllium chloride to form silver chloride and beryllium nitrate , the coefficients in the equation are;  2,1,2,1

Answer:

6.62m/s

Explanation:

Given data

M1= 120kg

U1= 5.5m/s

M2= 105kg

U2= 7.9m/s

The system experiences an inelastic collision, the expression for inelastic collision is

M1U1+ M2U1= (M1+M2)V

Subsitute

120*5.5+ 105*7.9= (120+105)*V

660+ 829.5= (225)*V

1489.5= (225)*V

Divide both sides by 225

V= 1489.5/225

V= 6.62m/s

Hence the common velocity is 6.62m/s

Answer:

[tex]X=165 \textdegree[/tex]

Explanation:

From the question we are told that:

Wavelength [tex]\lambda =360m[/tex]

Angle [tex]\theta=90 \textdegree[/tex]

Distance variation [tex]d=130m[/tex]

Generally the equation for phase difference X is mathematically given by

 [tex]X=\theta+\frac{d}{\lambda}*100[/tex]

 [tex]X=90+\frac{150}{360}*100[/tex]

 [tex]X=165 \textdegree[/tex]

Therefore Phase difference X is given as

 [tex]X=165 \textdegree[/tex]

Answer:

Hello There!!

Explanation:

Work done= force × distance moved

Work done=5000N×15m

Work done=75,000J

hope this helps,have a great day!!

~Pinky~

Answer:

tornado and land

Explanation:

Answer:

in case they lose control going downhill.

Explanation:

which is why they usually have a steep incline and are quite long. You see them used typically when the trucks brakes fail.