A train starts from rest (at position zero) and moves with constant acceleration. On the first observation, its velocity is 20m/s and 80seconds later the velocity became 60m/s. At 80s calculate the position, average velocity, and the constant acceleration over the interval.(7-points)

Answer:

Explanation:

The air enters their lungs at the same pressure as the water at that depth.

If they hold their breath as they rise to atmospheric pressure, the expanding volume of air (due to decreasing pressure) trapped in their lungs will hyperextend the alveoli in their lungs, likely tearing blood lines and risking death by drowning in their own blood.

Answer:

It tell you that the velocity is constant, what means that there's no acceleration

Answer:

To first order  f' = f (1 - u/c) where observer and source are separating

f' = (1 + .4) = 70 MHz   so (d) would be correct

The next term would be 1/2 (u/c)^2 = 1/2 * ,4^2 = .08 and the correction would be .08 * 50 = 4 Mhz

Most approximations would use (d).

Answer:Acupressure

.

.

..

But why post this question in Physics

Explanation:

It took [tex]t_1 =1.5\:\text{s}[/tex] for the sound to reach the 1st wall and at the same time time, the same sound took [tex]t_2 = 2.5\:\text{s}[/tex] to reach the 2nd wall. Assuming that the sound travels at 343 m/s, then let [tex]x_1[/tex] be the distance of the person to the 1st wall and [tex]x_2[/tex] be the distance to the 2nd wall. So the distance between the walls X is

[tex]X = x_1 + x_2 = v_st_1 + v_st_2 = v_s(t_1 + t_2)[/tex]

[tex]\:\:\:\:\:= (343\:\text{m/s})(4.0\:\text{s}) = 1372\:\text{m}[/tex]

Answer:

you will stc ohxoyxct txxtx xigigjjgjvvixiffjz,iffzikzfjvixii. hi h ohigiogooigoh

Explanation:

k jjvhvojvovvojivivivihvi hj

using newtons law

[tex]\\ \rm\Rrightarrow Force=Mass(Acceleration)[/tex]

[tex]\\ \rm\Rrightarrow Mass=\dfrac{Force}{Acceleration}[/tex]

[tex]\\ \rm\Rrightarrow Mass=\dfrac{500}{2}[/tex]

[tex]\\ \rm\Rrightarrow Mass=250kg[/tex]

Answer:

plz mark me as brainliest plz

Explanation:

The gravitational force of the earth keeps us bound to the earth. Gravitational force between earth and sun makes the earth move around the sun. Gravitational force between moon and earth makes the moon go around the earth.

Answer:

[tex]y=\frac{1}{2}x-2[/tex]

Explanation:

Slope-intercept form means we want the y to be by itself in the equation. Every thing we do will be about getting the y alone on the left side of the equation

To start we should move x to the left hand side. We can do this by subtracting x from both sides. That way, there is an x on the right, but not the left.

x-x-2y=4-x

this gives us

-2y=4-x

Great! So now what? Well, the y isn't by itself yet because it still is being multiplied by negative two (-2). In order to move it from the left side to the right side, we have to do the opposite of multiply; divide. So, we will divide both sides by -2

[tex]\frac{-2y}{-2} =\frac{4}{-2} -\frac{x}{-2}[/tex]

-2 divided by -2 is 1, 4 divided by -2 is -2, and -x divided by -2 is [tex]\frac{1}{2}x[/tex]

This gives us the answer:  [tex]y=\frac{1}{2}x-2[/tex]

Tips:

A negative divided by a negative is a positive ex: -4 divided by -2 is positive 2

If you are subtracting by a negative number, you are actually adding by a positive ex: 2-(-2) is actually 2+2

Don't be afraid to have fractions in your equations

Whatever you do to the one side of the equation, you must do it to the other side as well. Multiply the left side by 2? You HAVE TO multiply the right side by two as well. Add 3 to the right side? You HAVE TO add 3 to the left.

For problems like this (and when you have access to the internet), where you need to rewrite an equation, double check your work on desmos, which is an online graphing calculator. Input both the original equation and the equation you rewrote, and if they don't create the same line, you did something wrong.

Answer:

I think 9.5

Explanation:

............

Answer:

I think the answer is A...I'm not sure

Explanation:

A=(6,4)

B=(-2,-1)

A-B=(6-(-2)),(4-(-1))

=(6+2),(4+1)

=(8,5)

Answer:

[tex]6-(-2)=[/tex]

[tex]6+2[/tex]

[tex]=8[/tex]

[tex]4-\left(-1\right)[/tex]

[tex]=4+1[/tex]

[tex]=5[/tex]

[tex](8,5)[/tex]

[tex]\textbf{OAmalOHopeO}[/tex]

Answer:

1 millions times stronger

Answer:

The electrical energy stored in the capacitor will be cut in half.

Explanation:

The energy in a capacitator is given by E=C[tex]V^{2}[/tex]/2 and the formula for the Capacitance in a capacitator is C= [tex]\frac{Q}{V}[/tex] = ε[tex]\frac{A}{d}[/tex] .

So if we replace C = ε[tex]\frac{A}{d}[/tex]  in the first equation we have:

E = ε[tex]\frac{AV^{2} }{2d}[/tex]

Answer: 2.9kg

let mass be=m ; F=15N; Sin(theta)=32°;g =9.8kgm/s^2.

represent the mass. By resolving forces, we have:

F=mgSin(theta)

15N=mgSin(32°)

m=15N/g×Sin(32°)

m=15N/9.8m/s^2÷Sin(32°)

=2.888kg2.888

≈2.9kg

Mass on a string will be 2.9 kg

Object at equilibrium is the condition in which all the forces are balanced and the object will not accelerate and net force on the object will be zero

given

mass = ?

Force = F = 15N

angle from the vertical = 32°

according to newton' s law of equation, because of equilibrium condition

mg sin(32°) - F =0

m(9.8) (0.5299) - 15 =0

5.19302 m = 15

m= 15/5.19302 = 2.8885 = 2.9 kg

Mass on a string will be 2.9 kg

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All the answers are:

a) The time that will it take to rise to the highest point is 3.06 seconds.

b) The ball will rise to a height of 45.87 meters.

c) The time at which the ball will have a velocity of 10 m/s upward is 2.04 seconds.

The time when the ball has 10 m/s downward is 1.02 seconds.

d) The displacement of the ball will be zero at 6.12 seconds.

e) The time when the magnitude of the ball's velocity is equal to half its velocity of projection is 1.53 seconds.

f) The ball's displacement is equal to half the maximum height to which it rises after 0.90 seconds.

g) In each moment (upward and downward) the magnitude of the acceleration is the value of g (9.81 m/s²) and is a vector in the negative y-direction.

Let's calculate the values for each case.

a) At the highest point, the final velocity is 0, so we can use the following equation.  

[tex]v_{f}=v_{i}-gt[/tex] (1)

Where:

We know that v(i) = 30 m/s.

[tex]0=30-9.81t[/tex]

Solve it for t:

[tex]t=3.06\: s[/tex]

Hence, the time is 3.06 s.

b) At the highest point, the final velocity is 0, so we can use the following equation.  

[tex]v_{f}^{2}=v_{i}^{2}-2gh[/tex] (2)

[tex]0=v_{i}^{2}-2gh[/tex]

We know that the initial velocity is 30 m/s.

[tex]0=30^{2}-2gh[/tex]

Solving it for h we have:  

[tex]h=\frac{30^{2}}{2*9.81}[/tex]

[tex]h=45.87 \: m[/tex]

Then, the height is 45.87 m.

c) Using equation (1) we can find the time (t).

[tex]10=30-(9.81t)[/tex]

So, the time elapsed to get 10 m/s is:

[tex]t_{upward}=2.04\: s[/tex]

We know the upward time is equal to the downward time. So the time from v=10 m/s to v=0 m/s will be.

[tex]t_{upward}=2.04+t[/tex]  

[tex]t=1.02\: s[/tex]

This is the time when the ball has 10 m/s downward.          

Therefore, the time upward is 2.04 s, and the time downward is 1.02 s.

d) It will be when the ball returns to the ground.

[tex]t=2t_{upward}[/tex]

[tex]t=2*3.06[/tex]      

[tex]t=6.12\: s[/tex]

The displacement will be zero after 6.12 s.  

e) Here we need to find the time when v(f) is 15 m/s

[tex]15=30-gt[/tex]

[tex]t=\frac{15}{9.81}[/tex]  

[tex]t=1.53\: s[/tex]

The time when the v(f) is 15 m/s is 1.53 s.

f) Here, we need to find t when h = 45.87/2 m = 22.94 m

We can use the next equation:

[tex]h=v_{i}t-0.5gt^{2}/tex]

[tex]22.94=30t-0.5*9.81*t^{2}/tex]

Solving this quadratic equation, t will be:

[tex]t=0.90\: s/tex]

Hence, the ball's displacement is equal to half the maximum h, at 0.90 s.

g) In each moment the magnitude of the acceleration is the value of g (9.81 m/s²) and is a vector in the negative y-direction.

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Answer:

Approximating the Milky Way as a disk and using the density in the solar neighborhood, there are about 100 billion stars in the Milky Way.

Explanation:

Since we are making an order of magnitude estimate, we will make a series of simplifying assumptions to get an answer that is roughly right.

Let's model the Milky Way galaxy as a disk.

The volume of a disk is:

V

=

π

⋅

r

2

⋅

h

Plugging in our numbers (and assuming that

π

≈

3

)

V

=

π

⋅

(

10

21

m

)

2

⋅

(

10

19

m

)

V

=

3

×

10

61

m

3

Is the approximate volume of the Milky Way.

Now, all we need to do is find how many stars per cubic meter (

ρ

) are in the Milky Way and we can find the total number of stars.

Let's look at the neighborhood around the Sun. We know that in a sphere with a radius of

4

×

10

16

m there is exactly one star (the Sun), after that you hit other stars. We can use that to estimate a rough density for the Milky Way.

ρ

=

n

V

Using the volume of a sphere

V

=

4

3

π

r

3

ρ

=

1

4

3

π

(

4

×

10

16

m

)

3

ρ

=

1

256

10

−

48

stars /

m

3

Going back to the density equation:

ρ

=

n

V

n

=

ρ

V

Plugging in the density of the solar neighborhood and the volume of the Milky Way:

n

=

(

1

256

10

−

48

m

−

3

)

⋅

(

3

×

10

61

m

3

)

n

=

3

256

10

13

n

=

1

×

10

11

stars (or 100 billion stars)

Is this reasonable? Other estimates say that there are are 100-400 billion stars in the Milky Way. This is exactly what we found.

Answer:

Mercury, 46,001,272 km from the sun at the nearest point.

Explanation:

i'm pretty sure the answer is A wider

Electric lines of force where intensity of electric field is maximum when its wider.

The physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them, is known as an electric field (also known as an E-field. It can also refer to a system of charged particles' physical field.

Electric charges and time-varying electric currents are the building blocks of electric fields. The electromagnetic field, one of the four fundamental interactions (also known as forces) of nature, manifests itself in both electric and magnetic fields.

Electrical technology makes use of electric fields, which are significant in many branches of physics. For instance, in atomic physics and chemistry, the electric field acts as an attracting force to hold atoms' atomic nuclei and electrons together.

Therefore, Electric lines of force where intensity of electric field is maximum when its wider.

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We know

[tex]\boxed{\sf m=-\dfrac{v}{u}}[/tex]

[tex]\\ \sf\longmapsto 3=-\dfrac{-40}{u}[/tex]

[tex]\\ \sf\longmapsto 3=\dfrac{40}{u}[/tex]

[tex]\\ \sf\longmapsto u=\dfrac{40}{3}[/tex]

[tex]\\ \sf\longmapsto u=13.3cm[/tex]

Answer:

Level 1-

1. It depends of the sense and the magnitude of the force

2. Electric force

3. A contact force need to touch to act in the object, like push a box for example. A non-contact force don't need to touch to act in the object, like an magnet attracting other magnet

4. The pressure is the force divided by the area. The unit for pressure in the international system is Pascal

5. Because the pressure is applied in all the surface of our bodies, so the force is divided by the surface area of our bodies.

Level 2-

1. The balloons stick to the walls because when she rubbed they in her clothes they earned eletric charge, and when they touched the wall, the electric charges of the wall got polarized and it creats a attraction force.

The same happened with the water stream. The balloons were charged with electric charges and the water was attracted by it.

2. Mass is the amount of matter, it's an scalar quantity. Weight is the force created by the attraction of a massive body as the Earth, and another body as a human, and a force is a vector

3. It's for increase the surface area, so the pressure will be decreased

4. When a person pulls up the syringe plunger the pressure inside the syringe is smaller than the pressure outside, so the pressure push the liquid into the syringe

5. a) The stream of the top is falling closer than the stream from the bottom, causa in the top the pressure is lower than in the bottom. In the bottom, beyond the air pressure, it has also the whole column of water making more pressure, so it goes far.

b) The streams are all near because the holes are in the same height, so the pressure is divided for all the holes.

Level 3-

1. The girl.

pressure of the girl: 50/1 = 50

pressure of the man: 100/25 = 4

pressure of the elephant: 4500/250 = 18

So, the girl exerts more pressure.

2. When the can is heated the air inside expands and get out of it. If you seal the mouth of the can, the air cannot return to inside it, and when it get colder the air inside will shrink back to the normal volume, so it will occupy less space and the outside pressure will exerts a force and deform the can.

Answer:

towards the west

One can conclude that the magnetic field must have a component towards the east. The correct option is c.

A magnetic field is a vector field that describes the magnetic influence on moving charges, currents, and magnetic materials.

A moving charge in a magnetic field is subjected to a force that is perpendicular to both its own velocity and the magnetic field.

Every magnet possesses a north as well as a south pole. The opposite poles attract each other, whereas the same poles repel each other.

When you rub a piece of iron against a magnet, the atoms' north-seeking poles line up in the same direction.

Moving north, a proton enters a magnetic field. The proton curves downward as a result of this field. We can conclude that the magnetic field must have an eastward component.

Thus, the correct option is c.

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First, balance the reaction:

_ KClO₃   ==>   _ KCl + _ O₂

As is, there are 3 O's on the left and 2 O's on the right, so there needs to be a 2:3 ratio of KClO₃ to O₂. Then there are 2 K's and 2 Cl's among the reactants, so we have a 1:1 ratio of KClO₃ to KCl :

2 KClO₃   ==>   2 KCl + 3 O₂

Since we start with a known quantity of O₂, let's divide each coefficient by 3.

2/3 KClO₃   ==>   2/3 KCl + O₂

Next, look up the molar masses of each element involved:

• K: 39.0983 g/mol

• Cl: 35.453 g/mol

• O: 15.999 g/mol

Convert 10 g of O₂ to moles:

(10 g) / (31.998 g/mol) ≈ 0.31252 mol

The balanced reaction shows that we need 2/3 mol KClO₃ for every mole of O₂. So to produce 10 g of O₂, we need

(2/3 (mol KClO₃)/(mol O₂)) × (0.31252 mol O₂) ≈ 0.20835 mol KClO₃

KClO₃ has a total molar mass of about 122.549 g/mol. Then the reaction requires a mass of

(0.20835 mol) × (122.549 g/mol) ≈ 25.532 g

of KClO₃.

Hydrogen bomb is more powerful than atom bomb

Explanation:

Energy utilization focuses on technologies that can lead to new and potentially more efficient ways of using electricity in residential, commercial and industrial settings—as well as in the transportation sector

The resistance R = 20 Ω

The capacitance C = 106.1 μF

The current, I is 2.773 A at 56.31°.

The phase angle of the between the current and the voltage is 56.31° leading.

Since the impedance Z = 20 - j30 Ω, the resistance, R is the real part of the impedance. So R = ReZ = 20 Ω

So, the resistance R = 20 Ω

To find the capacitance, we need first to find the reactance of the capacitor X. Since the impedance Z = 20 - j30, the reactance of the capacitor X. is the imaginary part of the impedance. So X = ImZ = 30 Ω.

Now the reactance of the capacitor X = 1/ωC where ω = angular frequency of the circuit = 2πf where f = frequency of the circuit = 50 Hz and C = capacitance  

So, C = 1/ωX = 1/2πfX

Substituting the values of the variables into the equation, we have

C = 1/2πfX

C = 1/(2π × 50 Hz × 30 Ω)

C = 1/3000π

C = 1/9424.778

C = 1.061 × 10⁻⁴ F

C = 106.1 × 10⁻⁶ F

C = 106.1 μF

So, the capacitance is 106.1 μF

The current I = V/Z where V = voltage = 100 V at 0° and Z = impedance.

The magnitude of Z = √(20² + (-30)²)

= √(400 + 900)

= √1300

= 36.06 Ω

and its angle Φ = tan⁻¹(ImZ/ReZ)

= tan⁻¹(-30/20)

= tan⁻¹(-1.5) = -56.31°

So, V = 100 ∠ 0° and Z = 36.06 ∠ -56.31°

So, the current, I = V/Z =  (100 ∠ 0°)/36.06 ∠ -56.31°

= 100/36.06 ∠(0° - (-56.31° ))

= 2.773 ∠ 56.31° A

So, the current is 2.773 A at 56.31°.

Since the current is 2.773 A at 56.31°, the phase angle of the between the current and the voltage is 56.31° leading.

So, the phase angle of the between the current and the voltage is 56.31° leading.

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It stands for energy=mass times the speed of light squared.

All these people perform similar duties due to their similar profession.

All these People are the astronomers so they used various instruments that are present at their time in order to study the heavenly bodies such as stars and planets present in the sky. They also analyze their findings with the help of researches and experiments. They also develop theories that are based on personal observations and tested the theories of other astronomers in order to verify their theories.

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Explanation:

I=2.5 Ampere ; V=100V ;t = 1 hour=60secs

We know Heat = VIt

H=100×2.5×60=15,000J

Answer:

Explanation:

ASSUMING that block = sled AND that the rope is parallel to the slope.

The force acting parallel due to the weight is

13.6(9.81)sin35.5 = 77.475 N

The maximum friction force is

(0.45)13.6(9.81)cos35.5 = 48.877 N

If rope tension is T

77.475 - 48.877 < T < 77.475 + 48.877

            28.6 N < T < 126 N

28.6 N will occur if the block is on the verge of sliding downhill

126 N will occur if the block is on the verge of sliding uphill

Could be any value between them.

Two long parallel wires carry currents of 5.0 A and 8.0 A in the opposite direction. The wires are separated by 0.30 m. Find the magnetic force per unit length between the two wires.