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Answer:

False -> negative charge

Answer:

false

Explanation: electrons are negative charges

protons are positive charges

Answer:

cần cung cấp 70 độ vì nước sôi ở 100°C

Explanation:

Option ( iv ) is the correct answer.

A vector quantity the physical quantity that has both direction as well as magnitude.

Answer:

Elements in the same group have the same number of valence electrons.

When moving right across a period, the valence electrons of the main group elements increase by one.

When moving down a group, the valence electrons of the main group elements increase by one.

Elements in the same period have the same number of valence electrons.

Elements in the same period of the periodic table have valence electrons in the same energy levels.

When elements are in the same period on the periodic table, it means that they have the same number of shells.

The energy level of valence electrons in a atom depends on how far it is from the nucleus. This means that:

For instance, Boron, Carbon and Nitrogen will have valence electrons in the same energy levels.

In conclusion, elements in the same period will have valence electrons in the same energy levels.

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Answer:

Pascal is a derived unit because it cannot be expressed in any physics terms, but it is an expression of fundamental quantities.

Explanation:

[tex]{ \sf{Pasacal \: ( Pa) = \frac{newtons}{metres {}^{2} } }} \\ \\ { \sf{Pasacal \: (Pa) = \frac{kg \times {ms}^{ - 2} }{ {m}^{2} } }}[/tex]

Doppler frequency, the other car hear before they pass each other is 668.68 Hz.

Frequency is the number of occurrences of a repeating event per unit of time.

The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source.

According to the Doppler Effect, the frequency observed is

  [tex]fo=fs\frac{v+v_{o} }{v-v_{s} }[/tex]

[tex]f_{o}=595\frac{343+20 }{343-20 }\\f_{o} = 668.68 Hz[/tex]

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Answer:

The separation between the two stones is 36 m, when the second stone is approximately 10.9 m below the top of the cliff

Explanation:

The given parameters are;

The height of the cliff from which the stones are dropped, h = 60 m

The time at which the second stone is dropped = 1.6 seconds after the first

The distance below the top of the cliff when the distance between the two stones is 36 m = Required

We have;

The kinematic equation of motion that can be used is s = u·t - (1/2)·g·t²

For the first stone, we have, s₁ = u·t₁ - (1/2)·g·t₁²

For the second stone, we get; s₂ = u·t₂ - (1/2)·g·t₂²

t₁ = t₂ + 1.6

g = The acceleration due to gravity ≈ 9.81 m/s²

s = The distance below the cliff top

The initial velocity of the stones, u = 0

Let t represent the time from which the second stone is dropped at which the distance between the two stones is 36 m, we have;

s₁ = u·(t + 1.6) + (1/2)·g·(t + 1.6)²

s₂ = u·t + (1/2)·g·t²

u = 0

∴ s₁ - s₂ = 36 =  (1/2)·g·(t + 1.6)² - (1/2)·g·t²

2 × 36/(g) = (t + 1.6)² - t²  = t² + 3.2·t + 2.56 - t² = 3.2·t + 2.56

2 × 36/(9.81) = 3.2·t + 2.56

t = (2 × 36/(9.81) - 2.56)/3.2 =  ≈ 1.49 s

t ≈ 1.49 s

s₂ = (1/2)·g·t²

∴ s₂ = (1/2) × 9.81 × 1.49² ≈ 10.9

The distance below the top of the cliff of the second stone when the the separation between the two stones is 36 m, s₂ ≈ 10.9 m.

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Explanation:

Figure (8) shows a rod made up of copper and wood joined together. The rod is heated at the joint in the centre for about a minute. At which point – A, B, C or D, would it show the lowest temperature? PLEASE GIVE REASONS ALSO(MINIMUM 2)

Answer:

The average velocity of an object is its total displacement divided by the total time taken. In other words, it is the rate at which an object changes its position from one place to another.

Explanation:

Average velocity is a vector quantity. The SI unit is meters per second. However, any distance unit per any time unit can be used when necessary, such as miles per hour (mph) or kilometer per hour (kmph)

Answer:

the ratio of total displacement by total time taken

Answer:

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Answer:

1) The kinetic energy of the object after it drops for 2.0 seconds is approximately 384.9 Joules

2) The potential energy of the object after it drops for 2.0 seconds is approximately 204 J

Explanation:

1) The given mass of the object, m = 2.0 kg

The height from which the object is dropped, h = 30 m

The kinetic energy of the object after it drops for 2.0 seconds = Required

Kinetic energy, K.E. = (1/2)·m·v²

Where;

v = The velocity of the object

The kinematic equation for finding the velocity of the object is presented as follows;

v = u + g·t

Where;

u = The initial velocity of the object = 0

g = The acceleration due to gravity of the object ≈ 9.81 m/s²

t = The time of motion of the object = 2.0 seconds

∴ The velocity after 2 seconds, v ≈ 0 + 9.81 m/s² × 2 s = 19.62 m/s

The kinetic energy, K.E. after 2 seconds as the object drops is given as follows;

[tex]K.E._{(after \ two \ seconds)}[/tex] = (1/2) × 2.0 kg × (19.62 m/s)² = 384.9444 J ≈ 384.9 J

2) The total energy, M.E. of the object at the top, h = 30 m, u = 0, is given as follows;

The total mechanical energy, M.E. = P.E. + K.E.

M.E. = m·g·h + (1/2)·m·u²

∴ M.E. = 2.0 kg × 9.81 m/s² × 30 m + 0 = 588.6 J

M.E. = 588.6 J

Given that the total mechanical energy, M.E., is constant, we have;

At 2.0 seconds, M.E. = 588.6 J , K.E. ≈ 384.9 J, P.E. = M.E. - K.E.

∴ P.E. = 588.9 J - 384.9 J ≈ 204 J

The potential energy after it drops 2.0 seconds, P.E. ≈ 204 J

Explanation:

string roller is called an example of wheel and axel because The thin rod which needs to be turned is called the axle and the wider object fixed to the axle, on which we apply force is called the wheel.

hence the we apply force on the roller and the string gets tight.

Answer:

Explanation:

We first need to convert the 40 km/h to m/s. Going by the fact that 40 has only 1 significant figure in it, 40 km/h = 10 m/s. The rest of the values are in their proper labels. We will use the equation:

[tex]v^2=v_0^2+2a[/tex]Δx where the final velocity is 0 because the car is coming to a stop at the end; the initial velocity is 10 m/s, the acceleration (or, rather, deceleration) is -.5 m/s/s, and our unknown which is displacement. Filling in:

[tex]0=(10)^2+2(-.5)[/tex]Δx and solving for Δx:

Δx = [tex]\frac{-100}{2(-.5)}[/tex] which ends up being simply that

Δx = 100 m

Answer:

Explanation:

By being close to an atom that will gladly take the electrons being offered.

Suppose you are talking about Be. It is in the second column. It has two outer electrons that can be given away. It will not give away one of the two remaining electrons because they are too close to the + nucleus.

Along comes a Fluorine atom. It has 7 electrons in its outer ring. The chemistry of the situation allows it to take on one of the two electrons Be is offering. It is all a matter of charges and attractions.

Another Fluorine atom will take on the remaining electron from the Be. The outer ring cannot take on more than 1 electron, but that is enough

Answer:

But negative acceleration means that the rate of change of velocity is negative or velocity decreases. Example: (1) When we apply brakes in a moving car, then negative acceleration acts on it and the car stops. (2) When we throw a ball upwards, then also negative acceleration acts on it.

Explanation:

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MATHEMATICALLY A NEGATIVE ACCELERATION MEANS YOU WILL SUBTRACT FROM THE CURRENT VALUE OF THE VELOCITY.

[tex]\boxed{\sf W=Fscos\Theta}[/tex]

[tex]\\ \sf\longmapsto W=150(50)cos 60[/tex]

[tex]\\ \sf\longmapsto W=7500\times \dfrac{1}{2}[/tex]

[tex]\\ \sf\longmapsto W=3750J[/tex]

Radiation is energy that comes from a source and travels through space at the speed of light. This energy has an electric field and a magnetic field associated with it, and has wave-like properties. You could also call radiation “electromagnetic waves”.

cdc

Answer:

96 meters

Explanation:

d = st

d = (8 m/s)(12 s)

d = 96 m

Answer:

Explanation:

There is no pressure of your feet on the scales, and no pressure of the floor on the scales, so the scales will read zero*. Hence, your weight, in a freely falling lift is zero

Answer:

Wait until the end of the semester to complete all work.

Explanation:

this is the obvious answer.

please mark me brainliest

Answer:

Wait until the end of the semester to complete all work

Answer:

Because matter has been squeezed into a tiny space.

Explanation:

According to NASA, this can happen when a star is dying.

A black hole has no more gravity than the same amount of matter in any other form.

But remember that the gravitational forces are stronger as you get closer to the center of the body. The mass of a black hole is packed into such a small size (theoretically zero !) that you can get very close to its center. THAT'S where its gravity is hugely strong.

The magnitude (size or numerical value) and the direction.

Hope this helps!!! :)

Answer:

w = 0.01 t⁻²   rad/h

Explanation:

Let's use trigonometry to find the elevation angle of the telescope, we assume that the rocket remains fixed in the telescope.

        tan θ = CO / CA

the adjacent leg is CA = 16 km = 16 10³ m

Let's use kinematics to find the height of the rocket

          v = y / t

          y = v t

this height is equal to the opposite leg

          CO = v t

we substitute

         tan θ = vt / 16

         tan θ = 1200/16 t

         tan θ = 75 t

         θ = tan⁻¹ ( 75 t )

speed is defined by

          w = dθ/dt

          w = [tex]\frac{1}{1 + (75 t)^2} \ 75[/tex]  

as time increases we can neglect the 1 of the denominator

          w = 1/75 t²

          w = 0.0133 t⁻²

Using three significant figures

           w = 0.01 t⁻²   rad/h

for this answer the time must be given in hours

Answer:

If effort distance was 4 times, efficiency would be 100%.

Since it takes 5 times for effort distance, efficiency drops to output/input

output is 1*F

input is (1/4*F)*5

so: F/1/5*F/4 = 4F/5F = .8 or 80%

The efficiency of the lever is 80%.

To calculate the efficiency of the lever, we can use the formula for mechanical advantage and efficiency.

Mechanical Advantage (MA) is the ratio of the load (L) to the effort (E) in a lever system:

MA = Load / Effort

Given that the load is four times the effort applied:

Load = 4 * Effort

Also, the effort distance (dEffort) is five times the load distance (dLoad):

dEffort = 5 * dLoad

Now, we can write the formula for efficiency (η) of a lever system:

Efficiency (η) = (Mechanical Advantage / Ideal Mechanical Advantage) * 100%

The Ideal Mechanical Advantage (IMA) is the ratio of the effort distance to the load distance:

IMA = dEffort / dLoad

Substitute the given values into the IMA equation:

IMA = (5 * dLoad) / dLoad

IMA = 5

Now, we can calculate the Mechanical Advantage (MA) using the relationship between the load and effort:

MA = Load / Effort

MA = (4 * Effort) / Effort

MA = 4

Finally, we can calculate the efficiency (η):

Efficiency (η) = (Mechanical Advantage / Ideal Mechanical Advantage) * 100%

η = (4 / 5) * 100%

η = 0.8 * 100%

η = 80%

The efficiency of the lever is 80%.

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We know

[tex]\boxed{\sf Spring\:constant(K)=\dfrac{F}{x}}[/tex]

[tex]\\ \sf\longmapsto K=\dfrac{1}{0.5}[/tex]

[tex]\\ \sf\longmapsto K=2N/m[/tex]

Answer:

0.80 m

Explanation:

Neglecting friction, the total mechanical energy of the pendulum is constant.

E = K + U where K = kinetic energy and U = potential energy.

At its release point of 0.80 m, the pendulum bob has a mechanical energy which is equal to its potential energy, since, its initial kinetic energy is zero. By the time the bob swings to the other end, it has a mechanical energy equal to it initial potential energy since total energy is conserved.

Neglecting friction, the pendulum bob would swing back to its original height of 0.80 m since the total mechanical energy is conserved and at its highest point, it is purely potential energy.

So, the height the pendulum bob swings to after release from a height of 0.80 m neglecting fiction is 0.80 m.

Answer with Explanation:

Let me answer this in a simple way, since the density of stone is greater than that of water, the stone sinks as the weight of the stone is greater than the weight of water displaced by it. But the ship is designed in such a way that the relative density of the ship always becomes less than that of water. Therefore, the weight of the water displaced becomes equal to the total weight of the ship and thus it floats.

There are many other ways to explain this but this should give you the general idea.

Answer:

hi

Explanation:

pls mark as a BRAINLIST

Answer:

True

Explanation:

The bigger an object is, the more force you must apply to move the object. Think about it like moving a mouse compared to moving an elephant. You can't move the elephant by yourself, because you don't have enough strength or force to move it. But, you can easily pick up a mouse, because it requires less force, or strength. Hope this helped :)

Answer:

I don't know

Explanation:

sorry but I will help u next time kk