help me its emergency I need a correct answer please if you don't know then please dont guess​

Answer:

the skateboard pushes up

Explanation:

newton's 3rd law says for every action, there's an equal and opposite reaction, so when his feet push on the skateboard, the skateboard pushes back up.

Answer:

the skateboard pushes up

Explanation:

Answer:

[tex]\boxed{V_{i} = 5\ m/s}[/tex]

Explanation:

Given:

Acceleration = a = 0.75 m/s²

Time = t = ?

Final Velocity = [tex]V_{f}[/tex] = 72 km/hr = 20 m/s

Required:

Initial Velocity = [tex]V_{i}[/tex] = ?

Formula:

a = [tex]\frac{V_{f}-V_{i}}{t}[/tex]

Solution:

For  [tex]V_{i}[/tex]  the formula becomes:

[tex]V_{i} = V_{f}-at[/tex]

[tex]V_{i}[/tex]  = 20 - (0.75)(20)

[tex]V_{i}[/tex]  = 20 - 15

[tex]V_{i}[/tex]  = 5 m/s

In Case: If you want it in km/hr:

[tex]V_{i}[/tex]  = 5 * 3.6

[tex]V_{i}[/tex]  = 18 km/hr

Answer:

5 m/s

Explanation:

acceleration = 0.75 m/s²

time = 20 s

final velocity = 72 km/h = 20 m/s

initial velocity = ?

Apply formula for initial velocity.

[tex]u=-at+v[/tex]

[tex]\sf a=acceleration\\t=time\\v=final \: velocity\\u=initial \: velocity[/tex]

Solve for u.

[tex]u=-(0.75)(20)+ 20[/tex]

[tex]u=-15+20[/tex]

[tex]u= 5[/tex]

Answer:

B. A measure of mass per unit volume

Explanation:

Mass and volume are intimately correlated with density. In reality, it explains the precise nature of the connection between the two. We can determine an object's density by dividing its mass by volume. Thus, option B is correct.

The mass or amount per unit of volume of a substance determines its density. Density is calculated using the formula mass/volume. It is considered to have a low density if a mass has a high volume but a tiny mass.

The volume and subsequently the density of a material typically alter when it changes its phase or state of matter. Temperature is the primary component, even though pressure can also affect how a material changes state.

Water availability, climate, relief (the contour of the terrain), vegetation, soils, and the accessibility of renewable energy sources are physical elements that impact population density. Social, political, and economic variables altering humans all have an impact on population density.

Therefore,  A measure of mass per unit volume.

Learn more about density here:

https://brainly.com/question/29775886

#SPJ2

Answer:

You turn on the burner of a gas or stove - mechanical energy.

The gas ignites - Chemical energy.

The gas warms the water in the pan - Thermal energy.

Answer:

It would not be safe to walk out to where waves are breaking due to the effect of rip currents

Explanation:

The water depth in the surf zone is between 5 to 10 meters deep and with a wavelength of 30 meters, the speed of the wave is considerably fast such that control for safety may be difficult

Also the speed of the wave is directly related to the depth of the water which means that where the wave described above is fast as well as the rip current, also the water depth is expected to be considerable for a non swimmer

It is best to seek for sign post regarding safe areas and do not go into the water where there are no lifeguards or marked safe zones.

It won't be safe to walk out to where the waves are breaking.

This is because the wavelength is 30 meters which is a characteristic of

areas with significant water depth in the range of 5-11 meters.Under these

conditions the waves are usually very fast and may get swept with the

current from the water waves when trying to run from it.

It is recommended that we stay in areas where the depth is noted as not

being much and should always seek help and clarity from the life guards so

as to prevent drowning and death.

Read more on https://brainly.com/question/17125479

Answer:

The fly will travel 20 miles before the runners collide with each other.

Explanation:

Since the runners are both traveling at the same speed, they will meet and collide in the exact middle of each other which is 5 miles away from their starting point. Since they are traveling at 5 mph, it will take exactly one hour before they collide. The fly is going 20 mph so it will travel 20 miles before the runners collide in one hour.

Answer:

yes you can find a motor in a circuit

Answer:

The answer(s) for this question are as followed: A, C, & D

Explanation:

I hope this helped, let me know if i missed any.

Answer:

5.10×10⁻³ s

Explanation:

At terminal velocity, the acceleration is 0.

Sum of forces in the y direction:

∑F = ma

bv − mg = 0

mg = bv

m = bv / g

m/b = v/g

τ = v/g

τ = (5.00 cm/s) / (980 cm/s²)

τ = 5.10×10⁻³ s

Answer:

Sa is the salary of the governor of state A

Sb  is the salary of the governor of state A

"The governor of state A earns $53,745 more than the governor of state B. "

This means that:

Sa = Sb + $53,745

"If the total of their salaries is $289,405,"

means that:

Sa + Sb = $289,405

Then we have two equations:

Sa = Sb + $53,745

Sa + Sb = $289,405

Now, we can replace the first equation into the second equation:

(Sb + $53,745) + Sb = $289,405

2*Sb = $289,405 - $53,745 = $235,660

Sb = ($235,660)/2 = $117,830

and:

Sa = Sb +  $53,745 =  $117,830 + $53,745 = $171,575

Governor of state A earns:  $171,575

Governor of state B earns:  $117,830

Answer:

There are no gaps in space between the photons as they travel. If you look at light as a wave, then there no gaps unless specifically placed there on purpose. ... The light from a distance star indeed spreads out and weakens as it travels, but this just reduces the wave strength and does not introduce gaps.

I inferred you've referring to a close electrical circuit.

Answer:

The circuit is complete.

Explanation:

A closed electrical circuit is indeed a complete circuit. Also, it allows charges to flow, the bulbs in the circuit will shine and it is not broken.

It is termed closed circuit because there is no brokage in the series of electrical wires or the switch; which may prevent the free flow of current or charges. Thus, a feature that marks closed circuits is that they are complete.

Answer:

The circuit is complete.

Explanation:

Answer:

i. 6.923 V

ii. The e.m.f. = 22.5 V

Explanation:

i. The given parameters are;

Length of potentiometer = 1 m

The resistance of the potentiometer = 10 Ω

The e. m. f. of the attached cell = 9 V

The current, I flowing in the circuit = e. m. f/(Total resistance)

The current, I flowing in the circuit = 9 V/(10 + 3) = 9/13 A

The potential difference, p.d. across the 1 m potentiometer wire = I × Resistance of the potentiometer wire

The p.d. across the potentiometer wire = 9/13×10 = 90/13 = 6.923 V

ii) Given that the 1 m potentiometer wire has a resistance of 10 Ω, 75 cm which is 0.75 m will have an e.m.f. given by the following relation;

[tex]\dfrac{E}{R_{balance}} = \dfrac{V}{R_{cell}}[/tex]

Where:

E = e.m.f. of the balance point cell

[tex]R_{balance}[/tex] = Resistance of 75 cm of potentiometer wire  = 0.75×10 = 7.5 Ω

[tex]R_{cell}[/tex] = Resistance of the cell in the circuit = 3 Ω

V = e.m.f. attached cell = 9 V

[tex]\dfrac{E}{7.5} = \dfrac{9}{3}[/tex]

E = 7.5*3 = 22.5 V

The e.m.f. = 22.5 V

Answer:

1 j

2 C

3 H

4E

5A

Explanation:

Answer:

x=180√3. or 311.7 and y= 180km/h

Explanation:

y= sin30° × 360km/h

y= 0.5 × 360km/h

y= 180km/h

x=cos30° × 360 km/h

x=√3/2*360km/h

x=180√3. or 311.7

Answer: Contant.

Explanation:

You are given that When the boat moves the force of resistance is proportional to the velocity of the boat. This means that the total momentum on the boat is equal to zero. Then the boat remains at a certain position.

When a person walks from the stern to the bow of the boat, the boat will tend to move in the opposite direction with equal magnitude of momentum. The magnitude of forces will thereby cancel out.

The person will be seen moving while the boat moves in the opposite direction.

If no external force is acting on the boat, the sum of the momentum of the person and the boat will be equal to zero. And the boat will remain at rest.

The position of the boat long time after the person stopped moving will therefore remain the same.

Answer:

165.529454

Explanation:

According to the Pythagorean Theorem for calculating the lengths of a right angle triangle's sides, a^2 + b+2 = c^2, where c is the longest side (and the side opposing the right angle). So in your case it would be 150*150 + 70*70 = 27400. And √ 27400 is your answer.

Answer:

Infrasound vs. Ultrasound: Infrasound is sound that is below the lower limit of human hearing, below 20 Hz, and ultrasound is above the upper limit of human hearing, above 20,000 Hz.  Individuals use infrasound - this recurrence run for checking seismic tremors and volcanoes, graphing rock and oil developments underneath the earth. Infrasound is described by a capacity to get around hindrances with little scattering.  

For instance, a few creatures, for example, whales, elephants and giraffes convey utilizing infrasound over significant distances. Torrential slides, volcanoes, seismic tremors, sea waves, water falls and meteors produce infrasonic waves. Symptomatic ultrasound, additionally called sonography or demonstrative clinical sonography, is an imaging technique that utilizes high-recurrence sound waves to create pictures of structures inside your body. The pictures can give important data to diagnosing and treating an assortment of ailments and conditions.

Explanation:

idk how many words this is but its a start for u to add on to and i hope this helps and its in my own words - pls mark me brainiest

Answer:

Ultrasound vs. Infrasound Research Exploration

Beyond the limit of human hearing, ultrasound is above 20,000 Hz. Under the limit of human hearing, infrasound is below 20 Hz. Individuals use infrasound - this recurrence run for checking seismic tremors and volcanoes as well as graphing rock and oil developments beneath the earth. Infrasound is described by a capacity to get around hindrances with little scattering.  

For instance, creatures like whales, elephants and giraffes convey utilizing infrasound over significant distances. Torrential slides, volcanoes, seismic tremors, sea waves, waterfalls and meteors produce infrasonic waves. Symptomatic ultrasound, additionally called sonography or demonstrative clinical sonography, is an imaging technique that utilizes high-recurrence sound waves to create pictures of structures inside your body. The pictures can give important data to diagnosing and treating an assortment of ailments and conditions.

(Not turned in yet, but this is what i have so far. Good luck 8th graders <33)

-Sav xx

Answer:

Period of the signal.

Explanation:

So, this question is all about a concept in physics or astronomy which is called or known as Radiation Astronomy and Galactic Nuclei that are active. This concept talks most about Quasars; a powerful radiating object which derives its power from black holes.

When You take a look at Quasars, we get the to know that the more you think you can see, the more they move away from us.

Thus, when "You are observing the radiation from a distant active galaxy and you notice that the amplitude of the signal varies in strength regularly over a certain period. The maximum possible size for the source of this radiation can now be calculated from the "PERIOD OF THE SIGNAL.

NB: not the amplitude but the period.

Answer:

B. 6 s

Explanation:

Given in the y direction:

Δy = 0 m

v₀ = 30 m/s

a = -10 m/s²

Find: t

Δy = v₀ t + ½ at²

0 m = (30 m/s) t + ½ (-10 m/s²) t²

0 = 30t − 5t²

0 = 5t (6 − t)

t = 6

A ball is launched from the ground with a horizontal speed of 30 m/s and a vertical speed of 30 m/s, the ball will hit the ground again at approximately t = 6 seconds. The correct option is B.

We can examine the ball's vertical motion to predict when it will strike the ground once more.

h = v0t + (1/2)g[tex]t^2[/tex]

0 = 30t + (1/2)(9.8) [tex]t^2[/tex]

Simplifying the equation:

4.9 [tex]t^2[/tex] + 30t = 0

Factorizing the equation:

t(4.9t + 30) = 0

Solving for t in 4.9t + 30 = 0:

4.9t = -30

t = -30 / 4.9

t ≈ -6.1

Since time cannot be negative in this context, we discard the negative solution.

Therefore, the ball will hit the ground again at approximately t = 6 seconds.

Thus, the correct answer is B. 6 s.

For more details regarding vertical motion, visit:

https://brainly.com/question/12640444

#SPJ4

Answer:

[tex] 2.18\times 10^{-30} \:J[/tex]

Explanation:

[tex] K.E._{Electron}= \frac{1}{2} mv^2 \\\\

= \frac{1}{2} \times 9.11\times 10^{-31}\times (2.19\times 10)^2 \\\\

=4.555\times 10^{-31}\times 4.7961\times 10^2 \\\\

=4.555\times 10^{-31+2}\times 4.7961 \\\\

=21.8462355\times 10^{-29}\\

=2.18462355\times 10^{-30}\\

=2.18\times 10^{-30} \:J\\[/tex]

Answer:

Option B. 10 V.

Explanation:

The following data were obtained from the question:

Resistor 1 (R₁) = 20 Ω

Resistor 2 (R₂) = 40 Ω

Resistor 3 (R₃) = 60 Ω

Potential difference (V) = 60 V

Next, we shall determine the total resistance of the circuit.

The circuit is in series connection. Therefore the total resistance (R) can be obtained by adding up R₁, R₂ and R₃ together as shown below:

R = R₁ + R₂ + R₃

R = 20 + 40 + 60

R = 120 Ω

Therefore, the total resistance in the circuit is 120 Ω

Next, we shall determine the current flowing in the circuit.

Note: The same current will flow through each resistor since they are in series connection.

The current flowing in the circuit can be obtained as follow:

Potential difference (V) = 60 V

Total resistance (R) = 120 Ω

Current (I) =..?

V = IR

60 = I x 120

Divide both side by 120

I = 60/120

I = 0.5 A

Therefore, the current flowing in the circuit is 0.5 A

Now, we can calculate the potential drop across R₁ as follow:

Resistor 1 (R₁) = 20 Ω

Current (I) = 0.5 A

Potential difference cross R₁ (V₁) =.?

V₁ = IR₁

V₁ = 0.5 x 20

V₁ = 10 V

Therefore, the potential difference across R₁ is 10 V.

Answer:

        v = √k/m    x

Explanation:

We can solve this exercise using the energy conservation relationships

starting point. Fully compressed spring

        Em₀ = [tex]K_{e}[/tex] = ½ k x²

final point. Cart after leaving the spring

        [tex]Em_{f}[/tex] = K = ½ m v²

        Em₀ = Em_{f}

        ½ k x² = ½ m v²

        v = √k/m    x

Explanation:

To jump start she needs

1. Jumper cables

2. Power source/jump box/ portable batteries.

The positive end of the jump cable will be connected to terminal of the car battery and the jump box, likewise the negative terminal to complete the circuit for a successful jump start to be accomplished

Answer:

Destroy information about the speed of the particle

Explanation:

This is according to Heisenberg's Uncertainty Principle states that there is inherent uncertainty in the act of measuring a variable of a particle. Commonly applied to the position and momentum of a particle, the principle states that the more precisely the position is known the more uncertain the momentum is and vice versa.

Answer:

θ = 41.8º

Explanation:

This is an internal total reflection exercise, the equation that describes this process is

         sin θ = n₂ / n₁

where n₂ is the index of the incident medium and n₁ the other medium must be met n₁> n₂

        θ = sin⁻¹ n₂ / n₁

let's calculate

       θ = sin⁻¹ (1.00 / 1.50)

       θ = 41.8º

Answer:

actually quantity of matter present in a body is its mass.

The current does not change.

All three resistors are connected directly to the power source, and are unaware of each other.