a railway train 100m long passes over a bridge 400m long at 20ms.1 how long will it take to pass over the bridge ​

Answer: A. frequency

Explanation:

If it’s not wavelength then it has to be frequency

Answer: K

Explanation:

From the temperature readings given, we should note that 0°F is thesame as 32°C. Therefore, 0°C is colder than 0°F.

We should note that at 0K which is written as K, it is the coolest and it is often called the absolute zero because at this degree, there can't be anything that's colder.

Therefore, the answer is K

Answer:The powder of Kool Aid crystals are the solute. The water is the solvent and the delicious Kool Aid is the solution.... .-.

Explanation:

Answer:

- 0.3sin6000t A

Explanation:

Voltage, v = 10 cos 6000t V

Capacitance = 5-uF

Current flowing through, i(t)

i(t) = c * d/dt (V)

c = 5-uF = 5 * 10^-6 F

i(t) = (5 * 10^-6) * d/dt(10 cos 6000t)

d/dt(10 cos 6000t) = (10 * 6000) * (-sin 6000t)

Hence,

i(t) = (5*10^-6) * (10*6000) * (-sin 6000t)

i(t) = 5*10^-6 * 6*10^4 * - sin6000t

i(t) = 30 * 10^-2 * - sin6000t

i(t) = 0.3*-sin6000t

i(t) = - 0.3sin6000t Ampere

Answer:

D. Dissolve

Explanation:

A light wave is not a soluble substance, so it cannot dissolve. But it can totally  do A, B, and C.

Answer:

The maximum speed is 21.39 m/s.

Explanation:

Given;

radius of the flat curve, r₁ = 150 m

maximum speed, [tex]v_{max}[/tex] = 32.5 m/s

The maximum acceleration on the unbanked curve is calculated as;

[tex]a_c_{max} = \frac{V_{max}^2}{r} \\\\a_c_{max} = \frac{32.5^2}{150} \\\\a_c_{max} = 7.04 \ m/s^2[/tex]

the radius of the second flat curve, r₂ = 65.0 m

the maximum speed this unbanked curve should be rated is calculated as;

[tex]a_c_{max} = \frac{V_{max}^2}{r_2} \\\\V_{max}^2 = a_c_{max} \ \times \ r_2\\\\V_{max} = \sqrt{a_c_{max} \ \times \ r_2} \\\\V_{max} =\sqrt{7.04 \ \times \ 65} \\\\V_{max} = 21.39 \ m/s[/tex]

Therefore, the maximum speed is 21.39 m/s.

Answer:

[tex]v=5m/s[/tex]

Direction:SW(south-west)

Explanation:

From the question we are told that

Velocity and direction of Runner [tex]V_r= 5m/s ,East[/tex]

Velocity and direction of Air[tex]V_a= 4m/s ,South[/tex]

Generally the the resultant velocity v is mathematically given as

[tex]v=\sqrt{V_a^2+V_r^2}[/tex]

[tex]v=\sqrt{4^2+5^2}[/tex]

[tex]v=5m/s[/tex]

The resultant velocity is towards the south-west

Answer:

3.75Ns

Explanation:

Given data

F= 75N

time= 0.05seconds

We know that

P=Ft

substitute

P=75*0.05

P=3.75Ns

Answer:

The skateboard rolls away at 29.7 m/s

Explanation:

Law Of Conservation Of Linear Momentum

It states the total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and speed v is  

P=mv.  

If we have a system of bodies, then the total momentum is the sum of the individual momentums:

[tex]P=m_1v_1+m_2v_2[/tex]

If a collision occurs and the velocities change to v', the final momentum is:

[tex]P'=m_1v'_1+m_2v'_2[/tex]

Since the total momentum is conserved, then:

P = P'

[tex]m_1v_1+m_2v_2=m_1v'_1+m_2v'_2\qquad\qquad[1][/tex]

A girl of m1=50 kg rides an m2=4.9 kg skateboard and the common speed is v1=v2=2.1 m/s.

The girl jumps off the skateboard backward with a speed of v1'=-0.6 m/s (negative because it's opposite to the original direction). It's required to find the final speed of the skateboard. It will be calculated by solving for v2':

[tex]\displaystyle v'_2=\frac{m_1v_1+m_2v_2-m_1v'_1}{m_2}[/tex]

[tex]\displaystyle v'_2=\frac{50*2.1+4.9*2.1-50*(-0.6)}{4.9}[/tex]

Calculating:

[tex]\displaystyle v'_2=\frac{145.29}{4.9}=29.7\ m/s[/tex]

The skateboard rolls away at 29.7 m/s

Answer:

0 N/C

Explanation:

Since the electric field due toeach charge q is at the same distance from the center of the square and has a magnitude E = 2 N/C, we resolve the components of each electric field to vertical and horizontal.

So, for each charge, the magnitude of the horizontal component is E' = Ecos45 and the magnitude of the vertical component is E" = Esin45.

For the charges on the bottom half of the square, the direction of the vertical component is upwards and the horizontal components of their electric fields cancel out since they are in opposite directions, the resultant electric field due to the bottom two charges is 2Esin45.

For the charges at the upper half of the square, the direction of the vertical component is downwards and the horizontal components of their electric fields cancel out since they are in opposite directions, the resultant electric field due to the top two charges is -2Esin45.

So, the resultant electric field at the center of the square is thus 2Esin45 + (-2Esin45) = 2Esin45 - 2Esin45 = 0 N/C  

Answer:

65.59 m /s

Explanation:

Initial velocity u = 4.73 m/s

Final velocity v = ?

time t = 6.21 s

acceleration = g = 9.8 m /s

v = u + gt

= 4.73 + 9.8 x 6.21

= 65.59 m /s .

Answer: By a factor of 1/3.

Explanation:

For a photon with wavelength λ, the energy is written as:

E = h*c/λ

where:

h is the Planck's constant:

h = 6.63*10^(-34) Js

c is the speed of light:

c = 3*10^8 m/s

Now, if we triple the wavelength of this photon, then the energy will be:

E' = (h*c)/(3*λ)

We rewrite this as:

E' = (1/3)*(h*c/λ)

And (h*c/λ) was the previous energy:

(h*c/λ) = E

Then we can replace that in the above equation to get:

E' = (1/3)*(h*c/λ) = (1/3)*E

Then if we triple the wavelength, it will change the energy content of the individually radiated photons by a factor of 1/3.

Answer:

6.3 C

Explanation:

From the question,

Energy lost by the capacitor(half it stored energy) = 1/4CV².......................... Equation 1

Where C = Capacitance of the capacitor, V = Volatge across the parallel plate of the capacitor.

E = 1/4CV²

Given: C = 2.1 F, V = 6.0 V

Substitute these values into equation 1

E = 1/4(2.1)(6²)

E = 18.9 J

But,

E = 1/2QV..................... Equation 2

Where Q = amount of charge lost

Make Q the subject of the equation

Q = 2E/V................. Equation 3

Give: E = 18.9 J, V = 6.0 V

Q = 2(18.9)/6

Q = 6.3 C.

Answer:

10.8 s

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 0 m/s

Acceleration (a) = 5 m/s/s

Distance travelled (s) = 291 m

Time (t) taken =?

We can calculate the time taken for the car to cover the distance as follow:

s = ut + ½at²

291 = 0 × t + ½ × 5 × t²

291 = 0 + 2.5 × t²

291 = 2.5 × t²

Divide both side by 2.5

t² = 291 / 2.5

t² = 116.4

Take the square root of both side

t = √116.4

t = 10.8 s

Thus, it will take the car 10.8 s to cover the distance.

The time taken by the car to travel 291 m is calculated using the kinematics equation and it is obtained to be 10.8 seconds.

Here, it is given that;

The acceleration of the car is,

[tex]a = 5\,m/s^2[/tex]

The distance covered by the car is,

[tex]s = 291\,m[/tex]

Also, the car starts from rest, that means;

[tex]u = 0\,m/s[/tex]

We can use the second kinematics equation to find the time taken by the car to travel the given distance.

[tex]s = ut + \frac{1}{2}\,at^2\\291\,m = (0\,m/s \times t)+ \frac{1}{2} (5\,m/s^2\times t^2)\\\\\\291\,m = (2.5\,m/s^2\times t^2)[/tex]

implies

[tex]t = \sqrt{\frac{291\,m}{2.5\,m/s^2}}=10.78\,s\approx10.8\,s[/tex]

Learn more about 'motion in a straight line' here: https://brainly.com/question/19558242

Answer:

The current flowing through a resistor at a constant temperature is directly proportional to the potential difference across it. ... This is called Ohm's law.

Explanation:

I Looked It Up. So It May Be Wrong But I Hope This Helps!

Answer:

The current flowing through a resistor at a constant temperature is directly proportional to the potential difference across it. ... This is called Ohm's law.

Answer:

[tex]Q_{net}=4.38\,\,10^{-8}\,C[/tex]

Explanation:

We use Gauss's Law for the flux over a closed surface equal the net charge inside the closed surface divided the permitivity of space [tex]\epsilon_0=8.85\,\,10^{-12}\,\,\frac{C^2}{N*m^2}[/tex]

Therefore, by knowing the flux, we can estimate the net charge inside the cubic box with the product:

[tex]\Phi=\frac{Q_{net}}{\epsilon_0} \\Q_{net}=4950\,*\,8.85\,\,10^{-12} \,\,C\\Q_{net}=4.38\,\,10^{-8}\,C[/tex]

Answer:

higher, lower, external work, 100 %, work.

Explanation:

These paragraphs refer to the second law of thermodynamics. There are two statements for the second law of thermodynamics. They are as follows:

KELVIN STATEMENT:

All the heat from a source can never be transferred to the sink without the rejection of some heat.

CLAUSIUS STATEMENT:

Heat can not be transferred from a colder body to a hotter body without the application of som external work.

According to the statements the blanks can be filled as follows:

Heat naturally flows from an object that has a higher temperature to an object that has a Lower temperature. Heat can be made to flow in the reverse direction if external work is done. A machine can never have an efficiency of 100 %. This means that heat energy can never be fully converted into work energy.

Answer:

Heat naturally flows from an object that has a ______high_________ temperature to an object that has a ______lower_________ temperature. Heat can be made to flow in the reverse direction if _______work________ is done. A machine can never have an efficiency of ______100%_________. This means that heat energy can never be fully converted into _______mechanical energy________ energy.

Explanation: This is all derived from the Principles of the Second Law of Thermodynamics.

Answer:

A woman with a spike heel

Explanation:

Since we're assuming here, we proceed to assuming that the mass of the elephant is 6000 kg, and the mass of the lady is 60 kg. Then,

a woman with a spike heel will exert more pressure on the ground than an elephant weighing 6000 kg. This is because, the force exerted by the woman is a 588 N and she has a, say 1 cm² spike heel. This puts half her weight on each foot, and if evenly distributed to half on her heel and half on her sole, the pressure being exerted by each heel is 147 N/ 2cm² = 147 N/cm². On the other hand, if a 58,860 N elephant with an 1000 cm² feet is exerting 1/4 its weight on each foo. Then it has 14715 N/1000 cm² = 14.7 N/cm²; which is exactly 10 times lesser pressure than what the woman is exerting. So, the woman with the hell exerts more pressure, than the elephant will.

Answer:

c) True. If the coating cancels the light requested by the reflection, so there is more energy to enter the cell and therefore its efficiency increases

Explanation:

This exercise asks to analyze the effect of the antireflective coating on the efficiency of solar cells.

Let's start by expressing the expression for the interference of two light beams taken at when

* the phase change introduced when passing from air to 180º film

* the wavelength change by the refractive index of the film ln = lo / n

therefore the expression for destructive interference is

            2 n t = m λ

where m is an integer

with these concepts we can analyze the different statements

a) False. Phase shift does not change the wavelength of light

b) False. The refractive index of the solar cell is not affected by the refractive index of the film since the two materials do not mix.

c) True. If the coating cancels the light requested by the reflection, so there is more energy to enter the cell and therefore its efficiency increases

d) false. In solar cells the incidence is almost normal, therefore the effect of refraction (separation of colors for different angles) is very small

Answer:

nodes; antinodes

Explanation:

For standing waves, the areas where the amplitude is zero are referred to as nodes while the areas where the amplitude is at the maximum are known as antinodes.

A standing wave derives its feature primarily from the fact that there are certain points along the medium of transmission that are apparently seeing to be standing still with no displacement whatsoever. At the same time, there exist opposing points to the points of zero displacements. These points have a maximum displacement in both the positive and negative directions. While the former is referred to as nodal points, the latter is known as the antinodal points.

Given :

A wooden block is let go from a height of 5.80 m.

To Find :

The velocity of the block just before it hits the ground.

Solution :

We know, by equation of motion :

[tex]v^2 - u^2 = 2as[/tex]

Here, a = g = 9.8 m/s²( Acceleration due to gravity )

Putting all given values in above equation, we get :

[tex]v^2 - u^2 = 2as\\\\v^2 -0 = 2\times 9.8 \times 5.8 \\\\v = \sqrt{2\times 9.8 \times 5.8 } \ m/s\\\\v = 10.66\ m/s[/tex]

Hence, this is the required solution.

Answer:

the power used by the person is 10 W.

Explanation:

Given;

weight lifted, W = 50 N

distance through which the weight was lifted, d = 2 m

time of motion, t = 10 s

The power used by the person is calculated as;

[tex]P= FV\\\\P = F \ \times \ \frac{d}{t} \\\\P = 50 \ \times \ \frac{2}{10} \\\\P = 10 \ W[/tex]

Therefore, the power used by the person is 10 W.

Answer:

0.55 s

Explanation:

From the question given above, the following data were obtained:

Height (h) = 1.5 m

Horizontal velocity (v) = 25 m/s

Time of flight (t) =?

The time of flight of the potato talks about the total time spent by the potato in the air i.e the time taken for the potato to get to the ground..

Thus, we can obtain the time of flight of the potato as illustrated below:

Height (h) = 1.5 m

Acceleration due to gravity (g) = 9.8 m/s²

Time of flight (t) =?

H = ½gt²

1.5 = ½ × 9.8 × t²

1.5 = 4.9 × t²

Divide both side by 4.9

t² = 1.5 / 4.9

Take the square root of both side

t = √(1.5 / 4.9)

t = 0.55 s

Thus, the time of flight is 0.55 s

Answer:

a) 75000Joules

b) 0Joules

Explanation:

Workdone = Force * Distance

Given

distance= 750m

Force = 300N

a) If the frictional force = 200N

The Total force = 300N - 200N = 100N

Work done = 100 * 750

Workdone = 75,000Joules

Hence the workdone if the force of friction is 200N is 75,000Joules

b) If the frictional force = 300N

The Total force = 300N - 300N = 0N

Work done = 0* 750

Workdone = 0Joules

Hence the workdone if the force of friction is 300N is 0Joules i.e no work will be done on the sled

Answer:

[tex]a=2.5\ m/s^2[/tex]

Explanation:

Motion With Constant Acceleration

It's a type of motion in which the velocity of an object changes uniformly over time.

The equation that describes the change of velocities is:

[tex]v_f=v_o+at[/tex]

Where:

a   = acceleration

vo = initial speed

vf  = final speed

t    = time

Solving the equation for a:

[tex]\displaystyle a=\frac{v_f-v_o}{t}[/tex]

The ball starts at rest (vo=0) and rolls down an inclined plane that makes it reach a speed of vf=7.5 m/s in t=3 seconds.

The acceleration is:

[tex]\displaystyle a=\frac{7.5-0}{3}[/tex]

[tex]\boxed{a=2.5\ m/s^2}[/tex]

Answer:

122.735 behind converging lens ; 2.16

Explanation:

Given tgat:

Object distance, u = 29 cm

Image distance, v =

Focal length, f = - 19 (diverging lens)

Mirror formula :

1/u + 1/v = 1/f

1/29 + 1/v = - 1/19

1/v = - 1/19 - 1/29

1/v = −0.087114

v = −11.47916

v = -11.48

Second lens

Object distance :

u = 11.48 + 11 = 22.48 cm

1/v = 1/19 - 1/22.48

1/v = 0.0081475

v = 1 / 0.0081475

v = 122.735 cm

122.735 behind second lens

Magnification, m

m = m1 * m2

m = - v / u

Lens1 :

m1 = -11.48 / 29 = - 0.3958620

m2 = - 122.735 / 22.48 = - 5.4597419

Hence,

- 0.3958620 * - 5.4597419 = 2.16

Answer:

1264 Hz

Explanation:

We are given;

Your distance to the front of first speaker: L1 = 2.79 m

Distance between speakers; d = 1.26m

Now, your distance to second speaker can be calculated using pythagoras theorem.

Thus;

L2 = √(1.26² + 2.79²)

L2 = 3.0613 m

Let's find the wavelength from the formula;

(L1 - L2) = nλ

Where n is the order and could be; n = 0,1,2,3...

Making λ which is the wavelength the subject, we have;

(L1 - L2)/n = λ

The least frequency will occur at the wavelength when n = 1.

λ = (2.79 - 3.0613)/1

λ = -0.2713 m

We will take the absolute value and thus;

λ = 0.2713 m

Frequency is gotten from;

f = v/λ

Where v is speed of sound = 343 m/s

Thus;

f = 343/0.2713

f ≈ 1264 Hz

Answer:

Remains the same

Explanation: