All categories

2 years ago

Hi, please help me I need help.

Physics

1 answer:

sukhopar [10]2 years ago

4 0

Explanation:

Trains that use magnetic levitation (maglev) are suspended above the track, which greatly reduces friction from the rails and allows the trains to travel between 250 and 300 miles per hour! Magnetic levitation uses attractive and repulsive magnetic forces to suspend and control the speeds and motion of the trains.

You might be interested in

The hot glowing surfaces of stars emit energy in the form of electromagnetic radiation. It is a good approximation to assume tha

belka [17]

Given that,

Energy $H=2.7\times10^{31}\ W$

Surface temperature = 11000 K

Emissivity e =1

(a). We need to calculate the radius of the star

Using formula of energy

$H=Ae\sigma T^4$

$A=\dfrac{H}{e\sigma T^4}$

$4\pi R^2=\dfrac{H}{e\sigma T^4}$

$R^2=\dfrac{H}{e\sigma T^4\times4\pi}$

Put the value into the formula

$R=\sqrt{\dfrac{2.7\times10^{31}}{1\times5.67\times10^{-8}\times(11000)^4\times 4\pi}}$

$R=5.0\times10^{10}\ m$

(b). Given that,

Radiates energy $H=2.1\times10^{23}\ W$

Temperature T = 10000 K

We need to calculate the radius of the star

Using formula of radius

$R^2=\dfrac{H}{e\sigma T^4\times4\pi}$

Put the value into the formula

$R=\sqrt{\dfrac{2.1\times10^{23}}{1\times5.67\times10^{-8}\times(10000)^4\times4\pi}}$

$R=5.42\times10^{6}\ m$

Hence, (a). The radius of the star is $5.0\times10^{10}\ m$

(b). The radius of the star is $5.42\times10^{6}\ m$

8 0

3 years ago

Why does a bowling ball and a feather hit the ground at the same time when they are dropped in a vacuum?

AnnyKZ [126]

Answer:

See the explanation below.

Explanation:

This is because the vacuum chamber removes all the air contained and for this reason, there is no force that opposes the movement of the feather when falling. We must remember that the free fall equation of kinematics is not a function of the mass of an object.

$v_{f} =v_{o} +g*t$

where:

Vf = final velocity [m/s]

Vo = initial velocity [m/s]

g = gravity acceleration [m/s²]

t = time [s]

As we can see the mass of the object is not included in the equation.

8 0

3 years ago

A coil of wire contains N turns and has an electrical resistance R. The radius of each turn is a. Initially, inside the coil the

GuDViN [60]

Answer:

Using Faraday's law;

ε= -N ∆ψ(B)/ ∆t;

∆t= -N ∆ψ(B)/ ε

Explanation:

Using Faraday's law; Faraday's law state that the induced emf is directly proportional to the rate of change of time of magnetic flux

ε= -N ∆ψ(B)/ ∆t;

Where ε= induced EMF, ∆ψ(B)/ ∆t is the rate of change of magnetic flux, ψ(B) = BA cos θ

θ= the angle between the magnetic field B and the normal surface area.

We can also calculate the direction of induced magnetic flux. At first, the field is perpendicular to the plane of the loop,the loop can rotate about either an horizontal or vertical axis passing through the mid point

5 0

3 years ago

Which answer is a scientifically accurate description of velocity?

Tcecarenko [31]

The boat traveled from the dock north to the 200-meter marker in the bay in less than 5 minutes, giving the passengers several more hours to fish.

Explanation:

A boat traveling from the dock northward to a 200m mark in the bay in less than 5minutes giving the passengers several more hours to fish is a typical and best example of velocity description.

Velocity is the displacement of a body divided by the time taken.

Velocity = $\frac{displacement}{time}$

Displacement is the distance covered in a specific direction. Time is duration of the travel.

Velocity is a vector quantity that has both magnitude and direction. This implies that the value of velocity is recorded with a directional attribute.

We can say velocity is the speed of a body in a given direction

Only the last option gives the displacement of the body and the duration it traveled.

Learn more:

Velocity brainly.com/question/10883914

#learnwithBrainly

5 0

3 years ago

What advantage does absolute-age dating have over relative-age dating? Explain

kramer

Relative age is the age of a rock layer (or the fossils it contains) compared to other layers. It can be determined by looking at the position of rock layers. Absolute age is the numeric age of a layer of rocks or fossils. Absolute age can be determined by using radiometric dating.

8 0

3 years ago