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Natasha_Volkova [10]
3 years ago
14

A rock that contains enough of a particular substance to make it worth mining is called a(n) _____.

Physics
1 answer:
lora16 [44]3 years ago
4 0

Answer:

The answer is A .

Explanation:

Ore is a rock that requires mining .

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If a box with a mass of 8.0 kg is sitting on a frictionless surface and experiences an acceleration of 4.0 m/s2 to the right, wh
mr Goodwill [35]

The net force acting on a box of mass 8.0kg that experiences an acceleration of 4.0m/s² is 32N. Details about net force can be found below.

<h3>How to calculate net force?</h3>

The net force of a body can be calculated by multiplying the mass of the body by its acceleration as follows:

Force = mass × acceleration

According to this question, a box with a mass of 8.0 kg is sitting on a frictionless surface and experiences an acceleration of 4.0 m/s2 to the right.

Net force = 8kg × 4m/s²

Net force = 32N

Therefore, the net force acting on a box of mass 8.0kg that experiences an acceleration of 4.0m/s² is 32N.

Learn more about net force at: brainly.com/question/18031889

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4 0
2 years ago
True or false?
Ksju [112]

1. False

Explanation: it's exactly the opposite. In fact, Lenz's law states that the induced current and the induced emf in a conductor are generated in such a direction that opposes to the change in magnetic flux through the coil. This is summarized by the negative sign in the Faraday's Newmann Lenz law:

\epsilon= -\frac{d\Phi }{dt}

where \epsilon is the emf induced and \frac{d\Phi}{dt} is the rate of change of magnetic flux through the coil.

Lenz's law is a consequence of the law of conservation of energy. In fact, we have:

- If the magnetic flux through a coil is increasing, then the induced current has a direction such that the magnetic field generated by the coil is opposite to the direction of the external magnetic field, in order to decrease the total flux

- If the magnetic flux through a coil is decreasing, then the induced current has a direction such that the magnetic field generated by the coil is in the same direction as the external field, in order to increase the total flux

2. False

Explanation: the magnetic flux through a surface is given by

\Phi = BA cos \theta

where

B is the magnitude of the magnetic field

A is the surface area

\theta is the angle between the direction of B and the normal vector to the surface

As we see, the magnetic flux depends not only on B and A, but also on the orientation of the coil with respect to the magnetic field.

3. False

Explanation:

- Sound waves are mechanical waves: mechanical waves are waves consisting of oscillations of the particles in a medium. Due to their nature, therefore, mechanical waves can propagate only in the presence of a medium

- Electromagnetic waves are NOT mechanical waves: they consist of oscillations of electric and magnetic fields, in a direction perpendicular to the direction of propagation of the wave. Since em waves are not mechanical waves, they do NOT need a medium to propagate, since they can also travel through a vacuum; therefore the original statement is false.

5 0
2 years ago
A key falls from a bridge that is 45 m above the water. It falls directly into a model boat, moving with constant velocity, that
guapka [62]

Answer:

4m/s

Explanation:

The motion is in downward direction, and the boat is moving with constant velocity, the position of the boat horizontally is 12m before the key fall.

The height difference "h"= ( y- y°)= 45 m

We can determine the needed time the key requires to reach the water using the expression from Newton's law

h= v(o) + 1/2 at^2

g= acceleration due to gravity= 9.8m/s^2

h= v(o) + 1/2 gt^2 -------------------------eqn*)

V(o)= 0 for the key= initial velocity

h= height that the key falls= 45m

If we substitute the above values into eqn(*) we have

We can make t^2 subject of the formula since v(0)= 0

t^2= h/(1/2 g)

= 45/(1/2× 9.8)

t^2= 45/4.9=9.18

t= √9.18

t=3.03 secs

Since the boat was moving with constant velocity,

Then Velocity= distance/ time

= 12/3.03

Velocity= 4m/s

Hence, the speed of the boat is 4m/s

7 0
3 years ago
What are the functions of free falling?
Monica [59]

Answer:

In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it. In the context of general relativity, where gravitation is reduced to a space-time curvature, a body in free fall has no force acting on it.

Explanation:

3 0
3 years ago
Which is denser?<br><br> The water in a swimming pool or a quarter (coin).
PolarNik [594]

Answer:

The coin is denser than any of the liquids, and will sink through everything. The oil is the least dense liquid, so it will float on the water, and the syrup is the densest liquid, so it will sink below the water.

Explanation:

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4 0
3 years ago
Read 2 more answers
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