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wlad13 [49]
4 years ago
14

A car is brought to rest in a distance of 484m using a constant acceleration of -8.0m/s^2. What was the velocity of the car when

the acceleration first began?
Physics
1 answer:
Agata [3.3K]4 years ago
6 0

Answer:

88 m/s

Explanation:

To solve the problem, we can use the following SUVAT equation:

v^2-u^2=2ad

where

v is the final velocity

u is the initial velocity

a is the acceleration

d is the distance covered

For the car in this problem, we have

d = 484 m is the stopping distance

v = 0 is the final velocity

a=-8.0 m/s^2 is the acceleration

Solving for u, we find the initial velocity:

u=\sqrt{v^2-2ad}=\sqrt{-2(8.0)(484)}=88 m/s

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The emf induced in a coil that is rotating in a magnetic field will be at a maximum at which moment?
adelina 88 [10]
TLDR: It will reach a maximum when the angle between the area vector and the magnetic field vector are perpendicular to one another.

This is an example that requires you to investigate the properties that occur in electric generators; for example, hydroelectric dams produce electricity by forcing a coil to rotate in the presence of a magnetic field, generating a current.

To solve this, we need to understand the principles of electromotive forces and Lenz’ Law; changing the magnetic field conditions around anything with this potential causes an induced current in the wire that resists this change. This principle is known as Lenz’ Law, and can be described using equations that are specific to certain situations. For this, we need the two that are useful here:

e = -N•dI/dt; dI = ABcos(theta)

where “e” describes the electromotive force, “N” describes the number of loops in the coil, “dI” describes the change in magnetic flux, “dt” describes the change in time, “A” describes the area vector of the coil (this points perpendicular to the loops, intersecting it in open space), “B” describes the magnetic field vector, and theta describes the angle between the area and mag vectors.

Because the number of loops remains constant and the speed of the coils rotation isn’t up for us to decide, the only thing that can increase or decrease the emf is the change in magnetic flux, represented by ABcos(theta). The magnetic field and the size of the loop are also constant, so all we can control is the angle between the two. To generate the largest emf, we need cos(theta) to be as large as possible. To do this, we can search a graph of cos(theta) for the highest point. This occurs when theta equals 90 degrees, or a right angle. Therefore, the electromotive potential will reach a maximum when the angle between the area vector and the magnetic field vector are perpendicular to one another.

Hope this helps!
6 0
4 years ago
A person standing a certain distance from four identical loudspeakers is hearing a sound level intensity of 125 dB. What sound l
DENIUS [597]

Answer:

\mathbf{\beta = 123.75 \ dB}

Explanation:

From the question, using the expression:

125 \ dB = 10 \ log (\dfrac{I}{I_o})

where;

I_o = 10^{-12} \ W/m^2

I = 10^{12.5} \times 10^{-12} \ W/m^2

I = 3.162 \ W/m^2

This is a combined intensity of 4 speakers.

Thus, the intensity of 3 speakers = \dfrac{3.162\times 3}{4}

= 2.372 W/m²

Thus;

\beta = 10 \  log ( \dfrac{2.372}{10^{-12}} ) \ W/m^2

\mathbf{\beta = 123.75 \ dB}

7 0
3 years ago
Hello,help me with this out please i need it hurry but please ensure your answer is correct..I attach here with my question.
lilavasa [31]

Answer:

.409 N

Explanation:

For this to balance, the moments around the fulcrum must sum to zero.

On the left you have   .21   ( is that down? I will assume it is)

      Counterclockwise moments :

        .21 * 40     +  1.0 * 20    

     Clockwise moments :

        .5 * 20     +     F * 45

these moments must equal each other

.21*40 + 1 *20   =  .5 * 20 + F * 45

   F = .409 N

7 0
2 years ago
Planet A takes one year to go around the sun at a distance at a distance of one A U.. Planet B is three A U. from the sun. How m
kotykmax [81]
I would take roughly around 3 years
4 0
3 years ago
Is electricity a fuel
labwork [276]

YES, ELECTRICITY CONCERNS ENERGY WHICH IS USED AS A FUEL . IN MODERN DAY TECH, MOST MACHINES USE ELECTRICITY AS A FUEL SUCH AS THE ELECTRONIC TRAIN IN TOKYO, JAPAN.

8 0
2 years ago
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