Phát biểu nào sau đây là SAI?
A. Cường độ điện trường là đại lượng
đặc trưng cho điện trường về phương
diện tác dụng lực.
B. Điện trường tĩnh là điện trường có
cường độ E không đổi tại mọi điểm.
C. Đơn vị đo cường độ điện trường là
vôn trên mét (V/m).
D. Trong môi trường đẳng hướng,
cường độ điện trường giảm  lần so với
trong chân không

Answer:

Distance, S = 19.6 meters

Explanation:

Given the following data;

Time = 2 seconds

We know that acceleration due to gravity is equal to 9.8 m/s².

Also, the initial velocity of the object is equal to zero because it's starting from rest.

To find the total distance covered by the object, we would use the second equation of motion;

[tex] S = ut + \frac {1}{2}at^{2}[/tex]

Where;

Substituting into the equation, we have;

[tex] S = 0*2 + \frac {1}{2}*(9.8)*2^{2}[/tex]

[tex] S = 0 + 4.9*4[/tex]

[tex] S = 4.9*4 [/tex]

Distance, S = 19.6 meters

Therefore, the total distance covered by the object is 19.6 meters.

Answer:

1)[tex]t=2.26\: s[/tex]

2)[tex]S=33.9\: m[/tex]

3)[tex]v=26.77\: m/s[/tex]

4)[tex]\alpha=55.92[/tex]

Explanation:

1)

We can use the following equation:

[tex]y_{f}=y_{0}+v_{iy}t-0.5*g*t^{2}[/tex]

Here, the initial velocity in the y-direction is zero, the final y position is zero and the initial y position is 25 m.

[tex]0=25-0.5*9.81*t^{2}[/tex]

[tex]t=2.26\: s[/tex]

2)

The equation of the motion in the x-direction is:

[tex]v_{ix}=\frac{S}{t}[/tex]

[tex]15=\frac{S}{2.26}[/tex]

[tex]S=33.9\: m[/tex]

3)

The velocity in the y-direction of the stone will be:

[tex]v_{fy}=v_{iy}-gt[/tex]

[tex]v_{fy}=0-(9.81*2.26)[/tex]

[tex]v_{fy}=-22.17\: m/s[/tex]

Now, the velocity in the x-direction is 15 m/s then the velocity will be:

[tex]v=\sqrt{v_{x}^{2}+v_{fy}^{2}}=\sqrt{15^{2}+(-22.17)^{2}}[/tex]

[tex]v=26.77\: m/s[/tex]

4)

The angle of this velocity is:

[tex]tan(\alpha)=\frac{22.17}{15}[/tex]

[tex]\alpha=tan^{-1}(\frac{22.17}{15})[/tex]

[tex]\alpha=55.92[/tex]

Then α=55.92° negative from the x-direction.

I hope it helps you!

Answer:

1. Friction enables us to walk freely.

2. It helps to support ladder against wall.

3. It becomes possible to transfer one form of energy to another.

4. Objects can be piled up without slipping.

When you increase your speed from 35 mph to 70 mph, the force of impact you experience will be increased 4 times.

Hence, the correct option is B.

The force of impact in a collision is directly proportional to the square of the velocity. When the speed is doubled (increased from 35 mph to 70 mph), the force of impact will increase by a factor of four ([tex]2^2[/tex]). This is a fundamental concept in physics known as the kinetic energy formula, which is given by:

Kinetic Energy = (1/2) * mass * [tex]velocity^2[/tex]

Since kinetic energy is directly proportional to the square of velocity, doubling the speed results in four times the kinetic energy and, consequently, four times the force of impact.

Therefore, When you increase your speed from 35 mph to 70 mph, the force of impact you experience will be increased 4 times.

Hence, the correct option is B.

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Answer:

Option (b) is correct.

Explanation:

The amount of heat required to raise the temperature of substance of mass 1 kg by 1 degree C, is called specific heat of the substance.

The formula of the specific heat is

H = m c (T' - T)

where, m is the mass, c is the specific heat and T' - T is the change in temperature.

So, to know the rise in temperature, by adding the known amount of heat, the specific heat is required.

So, option (b) is correct.

Answer:

[tex]XY=636N[/tex]

Explanation:

From the question we are told that:

Distance [tex]d=0.35m[/tex]

Angle [tex]\theta=32\textdegree[/tex]

Force [tex]F=750N[/tex]

Generally the equation for magnitude of the stabilizing component of the brachialis force is mathematically given by

 [tex]XY=Fcos\theta[/tex]

 [tex]XY=750cos 32\textdegree[/tex]

 [tex]XY=636N[/tex]

Answer:

you can use G.oogle for this question.

Answer:

93.3 degrees Celsius.

Explanation:

Use the work-energy theorem to find the velocity of the block when it's released by the spring. The work done by the spring on the block as it's restored to equilibrium is

W = 1/2 kx ²

where k is the spring constant and x is the compression of the spring. So

W = 1/2 (1400 N/m) (0.170 m)² = 20.23 J

This is equal to the block's change in kinetic energy ∆K,

W = ∆K

and since it starts from rest, the initial K is zero, leaving us with

W = 1/2 mv ²

where m is the mass of the block and v is its speed, so that

20.23 J = 1/2 (0.200 kg) v ²

==>   v ≈ 14.2 m/s

The block slides at this speed across the frictionless surface until it hits the incline which introduces friction.

First, you need to find the length of the incline. It forms a 45° angle, and the underlying 45°-45°-90° triangle has a hypotenuse of length √2 (2.0 m) ≈ 2.83 m.

Next, you need to find the total work done on the block as it slides up the incline. Use Newton's second law to examine the forces acting on the block during this phase:

• the net force acting on the block in the direction perpendicular to the incline is

∑ F = n - mg cos(45°) = 0

where n = mg cos(45°) ≈ 1.39 N is the magnitude of the normal force and mg cos(45°) ≈ 1.39 N is the perpendicular component of the block's weight;

• the net force acting on the block parallel to the surface is

∑ F = -f - mg sin(45°) = ma

where f = µn = 0.210n ≈ 0.291 N is the magnitude of kinetic friction, mg sin(45°) ≈ 1.39 N is the parallel component of the weight, and a is the acceleration of the block.

Only the parallel forces do work on the block, and this work is negative because friction and weight oppose the block's sliding up the incline. The total work done on the block is then

W = (-0.291 N - 1.39 N) (2.83 m) ≈ -4.74 J

Use the work-energy theorem again to find the block's new speed v at the top of the incline:

W = ∆K

==>   -4.74 J = 1/2 (0.200 kg) v ² - 1/2 (0.200 kg) (14.2 m/s)²

==>   v ≈ 12.4 m/s

And now this becomes a projectile problem. The block travels a horizontal distance x after being launched at an angle of 45° with initial speed 12.4 m/s after time t according to

x = (12.4 m/s) cos(45°) t

Its height y from the 2.0 m-high surface at time t is given by

y = (12.4 m/s) sin(45°) t - 1/2 gt ²

The block lands on the surface when y = 0, which occurs after t ≈ 1.79 s, at which point the block has covered a distance d ≈ 15.7 m.

The block sail through the air at the distance of "15.8 m"

Given:

Spring constant,

Mass,

Block's coefficient,

By using Work energy theorem, we get

→ [tex]W_{spring}+W_g+W_f = KE_f-KE_i[/tex]

By substituting the values, we get

→ [tex]\frac{1}{2}\times 1400\times (0.17)^2- (0.2\times 9.8\times 2)-(0.21\times 0.2\times \frac{9.8}{\sqrt{2} }\times \sqrt{2}\times 2 )= \frac{1}{2}\times 0.2\times V_f^2[/tex]

here,

[tex]V_f = 12.44 \ m/s[/tex]

→ [tex]d = \frac{V_f^2 Sin 2 \Theta}{g}[/tex]

     [tex]= \frac{(12.44)^2 Sin 90^{\circ}}{9.8}[/tex]

     [tex]= 15.8 \ m[/tex]

Thus the answer above is right.  

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Answer:

17.5 m/s

Explanation:

Refer to the attachment!~

Answer:

The Distance traveled (in meters) by the jet as the observer watches the nose of the jet cross from one side of the moon to the other.

=145.5m

Explanation:

The radius of the circling jet r = 15.8km = 15.8*10^3 m

the angle subtended by moon

θ = 9.21*10^-3 rad

Therefore, the distance traveled by jet is

s = rθ

= (15.8*10^3 m)(9.21*10^-3 )

= (15,800)(0.00921)

=145.5m

Answer:

wavelength=75.0

speed of sound(v)=350 .0m/s

frequency(f)=?

we know,

v=f*wavelengh

350.0 =f*750

f. =350/75

=4.667

pls mark me brainlest

Answer:

150000 is the answer to the question

Answer:

venus......................

Answer:

concave mirror use in headlights and torches

Explanation:

Concave mirrors are used in headlights and torches. The shaving mirrors are also concave in nature since these mirrors can produce enlarged clear images. Doctors use concave mirrors as head mirrors to have a clearer view of eyes, noses, and ears. The dental mirrors used by dentists are also concave.

Answer:

B. 15 miles an hour going west

Answer: 4800 N/m

Explanation:

Given

mass of rock [tex]m=2.5\ kg[/tex]

Height of cliff [tex]h=32\ m[/tex]

compression in the spring [tex]x=57\ cm[/tex]

Here, potential energy is converted into kinetic energy which in turn converts to elastic potential energy of the spring

[tex]\Rightarrow mgh=\dfrac{1}{2}kx^2\\\\\Rightarrow k=\dfrac{2mgh}{x^2}\\\\\Rightarrow k=\dfrac{1568}{0.3249}\\\\\Rightarrow k=4826.100\approx 4800\ N/m[/tex]

Answer:

480

Explanation:

2021

Answer: Hazmat products are allowed in your FC are:

Explanation:

Hazmat products consist of flammable, corrosive and harmful substances which are actually very hazardous to human health and environment.  

Hazardous material allowed in FC are as follows.

So, hazmat allowed products are GPS unit (lithium batteries) and subwoofer (magnetized materials).

Thus, we can conclude that hazmat products are allowed in your FC are:

Answer:

A. 40 J

Explanation:

Given;

heat added to the system, Q = 70 J

work done by the system, W = 30 J

The change in the internal energy of the system is calculated using the first law of thermodynamic as shown below;

ΔU = Q - W

ΔU = 70 J - 30 J

ΔU = 40 J

Therefore, the  change in the internal energy of the system is 40J

Answer:

So as KE becomes 4times , Momentum will increase by 2 times.

Answer:

The ratio of the resistances of second coil to the first coil is the ratio of square of radius of the first coil to the square of radius of  second coil.

And

The ratio of the resistances of fourth coil to the third coil is the ratio of square of radius of the third coil to the square of radius of  fourth coil.

Explanation:

The resistance of the coil is directly proportional to the length of the coil and inversely proportional to the area of coil and hence inversely proportional to the square of radius of the coil.

So, the ratio of the resistances of second coil to the first coil is the ratio of square of radius of the first coil to the square of radius of  second coil.

And

The ratio of the resistances of fourth coil to the third coil is the ratio of square of radius of the third coil to the square of radius of  fourth coil.

Air is classified as a mixture. Option D is the correct answer.

Air is a combination of different gases, primarily nitrogen (about 78%), oxygen (about 21%), and small amounts of other gases such as carbon dioxide, argon, and trace elements. These gases are not chemically bonded to each other, but rather exist together in the same space. Option D is the correct answer.

In a mixture, the substances involved retain their individual properties and can be separated by physical means. This is true for air as well. The gases in air can be separated through processes like fractional distillation or filtration. It's important to note that air also contains other components such as water vapor, dust particles, and pollutants, which can vary in concentration depending on the location and environmental conditions. These components further contribute to the complex nature of air as a mixture.

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Đáp án:

 p=5,74atm

Giải thích các bước giải:

áp suất khí là:

pV=nRT⇒p=nRTV=1.0,082.(77+273)5=5,74atmpV=nRT⇒p=nRTV=1.0,082.(77+273)5=5,74atm

p=5,74atm

Giải thích các bước giải:

áp suất khí là:

pV=nRT⇒p=nRTV=1.0,082.(77+273)5=5,74atmpV=nRT⇒p=nRTV=1.0,082.(77+273)5=5,74atm

Answer:

Average speed = total distance traveled / total time traveled

V = (2 + 80) / (2 + 40) = 82 / 42 = 2 m / s

Explanation:

everything can be found in the picture

Answer:

D) all of the above.

Explanation:

First polarises it, cahrging and discharging occurs at once.

A negatively charged balloon touching a wooden wall then from the given options option D is correct which is all of the above.

Charged matter experiences a force when it is exposed to an electromagnetic field due to the physical property of electric charge. Positive or negative charges can exist in an electric field (commonly carried by protons and electrons, respectively).

Contrary charges attract one another, while like charges repel one another. A neutral object is one that carries no net charge. Classical electrodynamics, the name given to an early understanding of how charged particles interact, is still accurate for issues that do not call for taking into account quantum phenomena.

In the first step it polarizes molecules in the wall, then charging and discharging in the wall will take place at once.

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Answer:

Spell what?

Can u please mention that too?

Answer:

what

Explanation: how do you spell what please include this in your next post