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3 years ago

a 15kg child is riding a merry go round at 3rpm. what centripetal force must she exert if she is 8m from the center

1 answer:

8 0

This is another application of Newton's second law of motion

   Force = (mass) x (acceleration).

The quantities are a little more complicated in circular motion than
they are in plain old straight-line motion. In circular motion, the 'force'
is the centripetal force on the object, always pointing toward the center
of the circle. And the 'acceleration' is the centripetal acceleration, also
pointing toward the center of the circle, and equal to

      (speed)² / (radius).

The only thing we really need to find is the centripetal acceleration, and
then we'll have everything needed to plug into the formula and calculate
the centripetal force.

   Acceleration =    (speed)² / (radius).

   Speed = (distance) / (time) =

   (3 circumferences) / (minute) =

   (3 x 2pi x radius) / minute =

(6 pi x 8 meters) / (60 sec) = 0.8 pi m/s .

   Acceleration = (speed)² / (radius) =

   0.64 pi² m²/s² / (8 meters) = 0.08 pi² m/s² =

   0.79 m/s² (rounded) .

   Force = (mass) x (acceleration) =

   (15 kg) x (0.79 m/s²) = 11.84 newtons
      (about 2.66 pounds) .

I would not say that she "exerts this centripetal force". The fact of
the matter is much simpler: This is the force that something must
exert on her, pointing toward the center, in order to keep her revolving
around the center at that speed. It could be the friction between her
shoes and the platform, if she's standing on the merry-go-round.
It could be a rope tied between her ankle and something at the center
of the rotating platform. It could be the safety belt on the horse that
she's riding. Whatever it is, something has to constantly pull her toward
the center of the platform, with a force of 11.84 newtons, otherwise her
15kg body will not travel in that circular path.

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<u>Answer: </u>

For 1: The correct option is b.

For 2: The correct option is a.

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4 years ago

What is one of the principles of charges in a conductor?

nevsk [136]

Answer:

A conductor allows free charges to move about within it. The electrical forces around a conductor will cause free charges to move around inside the conductor until static equilibrium is reached. Any excess charge will collect along the surface of a conductor. Conductors with sharp corners or points will collect more charge at those points.

Explanation:

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3 years ago

Three forces act on a moving object. One force has a magnitude of 83.7 N and is directed due north. Another has a magnitude of 5

LekaFEV [45]

Answer:

$|\vec{F}_3| = 102.92 \ N$

$\theta = 57 \° 24 ' 48''$

Explanation:

For an object to move with constant velocity, the acceleration of the object must be zero:

$\vec{a} = \vec{0}$ .

As the net force equals acceleration multiplied by mass , this must mean:

$\vec{F}_{net} = m \vec{a} = m * \vec{0} = \vec{0}$ .

So, the sum of the three forces must be zero:

$\vec{F}_1 + \vec{F}_2 + \vec{F}_3 = \vec{0}$ ,

this implies:

$\vec{F}_3 = - \vec{F}_1 - \vec{F}_2$ .

To obtain this sum, its easier to work in Cartesian representation.

First we need to define an Frame of reference. Lets put the x axis unit vector $\hat{i}$ pointing east, with the y axis unit vector $\hat{j}$ pointing south, so the positive angle is south of east. For this, we got for the first force:

$\vec{F}_1 = 83.7 \ N \ (-\hat{j})$ ,

as is pointing north, and for the second force:

$\vec{F}_2 = 59.9 \ N \ (-\hat{i})$ ,

as is pointing west.

Now, our third force will be:

$\vec{F}_3 = - 83.7 \ N \ (-\hat{j}) - 59.9 \ N \ (-\hat{i})$

$\vec{F}_3 = 83.7 \ N \ \hat{j} + 59.9 \ N \ \hat{i}$

$\vec{F}_3 = (59.9 \ N , 83.7 \ N )$

But, we need the magnitude and the direction.

To find the magnitude, we can use the Pythagorean theorem.

$|\vec{R}| = \sqrt{R_x^2 + R_y^2}$

$|\vec{F}_3| = \sqrt{(59.9 \ N)^2 + (83.7 \ N)^2}$

$|\vec{F}_3| = 102.92 \ N$

this is the magnitude.

To find the direction, we can use:

$\theta = arctan(\frac{F_{3_y}}{F_{3_x}})$

$\theta = arctan(\frac{83.7 \ N }{ 59.9 \ N })$

$\theta = 57 \° 24 ' 48''$

and this is the angle south of east.

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3 years ago

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BaLLatris [955]

B. Because I say so

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3 years ago

I need help this is extremely hard

telo118 [61]

Answer:

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3 years ago