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bogdanovich [222]
3 years ago
13

An object is at rest on the ground. The object experiences a downward gravitational force from Earth. Which of the following pre

dictions is correct about why the object does not accelerate downward? Select two answers. Justify your selections.A) The bonded molecules of the object are repelled upward by the bonded molecules of the ground with the same magnitude as the gravitational force downward on the object.B)The normal force is exerted upward on the object from the ground with the same magnitude as the gravitational force downward on the objectC) The bonded molecules of the object are attracted downward by the bonded molecules of the ground with the same magnitude as the gravitational force downward on the object.D) The force of friction is exerted upward on the object from the ground with the same magnitude as the gravitational force downward on the object.
Physics
2 answers:
Montano1993 [528]3 years ago
6 0

Answer:

A) and B) are correct.

Explanation:

If the object is at rest, it means that no net force is exerted on it.

As the object experiences a downward gravitational force from Earth, in order to be at rest, it must experience an upward force with the same magnitude as the gravitational force on the object.

This force is supplied by the normal force, which can adopt any value in order to meet the condition imposed by Newton´s 2nd Law, and is always perpendicular to the surface on which the object is placed (in this case, the ground).

At a molecular level, this normal force is supplied by the bonded molecules of the ground that behave like small springs being compressed by the molecules of the object, exerting an upward restoring force upward on them.

So, the statements A) and B) are true.

KIM [24]3 years ago
4 0

Answer:

The bonded molecules of the object are repelled upward by the bonded molecules of the ground with the same magnitude as the gravitational force downward on the object.

The normal force is exerted upward on the object from the ground with the same magnitude as the gravitational force downward on the object.

Explanation:

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For what angle of incidence at the first mirror will this ray strike the midpoint of the second mirror (which is 28.0 cmcm long)
loris [4]

This question is incomplete, the complete question is;

Two plane mirrors intersect at right angles. A laser beam strikes the first of them at a point 11.5 cm from their point of intersection, as shown in the figure.

For what angle of incidence at the first mirror will this ray strike the midpoint of the second mirror (which is 28.0 cmcm long) after reflecting from the first mirror

Answer: angle of incidence is 39.4°

Explanation:

Given that;

two plain mirrors intersect at right angle (90°)

distance d = 11.5 cm

S = 28.0 cm

Now the angle that the reflection ray males with first the mirror equal theta  (∅)

so

tan∅ = (S/2) / d

tan∅ = (28/2) / 11.5

tan∅ = 14 / 11.5

tan∅ = 1.2173

∅ = tan⁻¹ (1.2173)

∅ = 50.6°

so angle of incidence = 90° - ∅

= 90° - 50.6°

= 39.4°

Therefore angle of incidence is 39.4°

5 0
3 years ago
You are attempting to row across a stream in your rowboat. Your paddling speed relative to still water is 3.0 m/s (i.e., if you
Nataliya [291]

Answer:

Please check the attached file for the diagram

Explanation:

The velocity of the of the rowboat V_{tot}  through the river is the resultant velocity. It is obtained taking a vector sum of the velocity in still water and the velocity of the river.

There are several ways to take this vector sum, but the question makes it simple for us to use Pythagoras's theorem because the East and North directions are perpendicular to each other.

Hence;

V_{tot}^2=V_{still}^2+V_{w}^2\\V_{tot}^2=3^2+4^2

V_{tot}=\sqrt{3^2+4^2}\\ V_{tot}=\sqrt{25}=5m/s

6 0
3 years ago
How will creat thunderstrom​
emmasim [6.3K]

Answer:

the air has to be unstable as well as it needs to be moved upwards.

Explanation:

it needs to be moved upwards and also needs to have unstable air.

3 0
2 years ago
How does the temperature affect the phase of water
Sever21 [200]

Answer:

Temperature affects phase change by slowing down the movement in between the atoms, thus causing a change in kinetic energy, which in turn causes the atoms to undergo forms of combining or a type of disepersion.

Explanation:

Kinetic energy while being the reason phase changes are constant, Kinetic Energy can be caused by other means. Pressure and temperature can affect many other states kinetic energy, which in turn can affect each state of matter. Making a group of atoms or compounds compacts will force the atoms to move closer together thus with a lower net kinetic energy energy. Reducing temperature also works along the same lines. Colder temperatures can slow down atomic movements which in turn will naturally make each atom move close to each other.

With all of the information provided, it is only feasible that pressure and temperature are directly corresponding with the matter and atomic phase change

8 0
2 years ago
Dylan has two cubes of iron. The larger cube has twice the mass of the smaller cube. He measures the smaller cube. Its mass is 2
liubo4ka [24]

Answer:

The volume of the larger cube is 5.08 g/cm³.

Explanation:

Given that,

Mass of smaller cube = 20 g

Density of smaller cube \rho= 7.87 g/cm^2

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The larger cube has twice the mass of the smaller cube.

M_{l}=2m_{s}

Density is same for both cubes because both cubes are same material.

The density is equal to the mass divided by the volume.

\rho=\dfrac{m}{V}

V=\dfrac{m}{\rho}

Where, V = volume

m = mass

\rho=density

We need to calculate the volume of smaller mass

The volume of smaller mass

V_{s}=\dfrac{m_{s}}{\rho_{s}}

V_{s}=\dfrac{20}{7.87}

V_{s}=2.54\ cm^3

Now, We need to calculate the volume of large cube

V_{l}=\dfrac{m_{l}}{\rho_{l}}

V_{l}=\dfrac{2\times20}{7.87}

V_{l}=5.08\ g/cm^3

Hence, The volume of the larger cube is 5.08 g/cm³.

8 0
3 years ago
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