Which of the statements best describes the relationship between the surface of an object and the amount of friction it produces?



A.) The smoother the surface of an object, the more friction it will produce.



B.) The softer the surface of an object, the more friction it will produce.



C.) The rougher the surface of an object, the more friction it will produce.



D.) The harder the surface of an object, the more friction it will produce.

The question seeks to determine values related to centripetal acceleration and other quantities in uniform circular motion, requiring application of principles from circular dynamics. Calculation specifics, however, demand additional information or clarification for accurate resolution.

The question pertains to determining specific quantities related to an object undergoing uniform circular motion. Given are the period T = 2.0 s, radius r = 3.00 m, and a centripetal acceleration vector a = (6.00 m/s2)i + (-4.00 m/s2)j at a certain instant. To resolve this, it's essential to understand that centripetal acceleration points towards the center of the circular path, and its magnitude in circular motion is given by ac = v2/r or implicitly through ac = 4π2r/T2, whereby v is the velocity of the object and T is the period of motion.

Part (a) involves finding v parallel to a, which cannot be directly inferred from the provided acceleration vector without additional context on the motion's direction. Part (b) requests the calculation of r cross a (r×a), a vector product that depends critically on both the magnitude and angle between the radius vector r and acceleration vector a, necessitating further geometric interpretation or additional information to solve accurately.

Final answer:

The final answers are: (a) [tex]\( v \cdot a = 0 \, \text{m}^2/\text{s}^3 \)[/tex] (b) [tex]\( r \cdot a = -4.00 \, \text{m}^2/\text{s}^2 \)[/tex]

Explanation:

- [tex]Period \( T = 4.30 \, \text{s} \)[/tex]

- [tex]Radius \( r = 3.00 \, \text{m} \)[/tex]

-[tex]Acceleration \( a = (5.00 \, \text{m/s}^2) \mathbf{i} + (-4.00 \, \text{m/s}^2) \mathbf{j} \)[/tex]

Calculate the velocity  v  using the formula for uniform circular motion:

[tex]\[ v = \frac{2 \pi r}{T} \][/tex]

Substitute the given values:

[tex]\[ v = \frac{2 \pi \times 3.00 \, \text{m}}{4.30 \, \text{s}} \approx 4.39 \, \text{m/s} \][/tex]

Calculate the dot product [tex]\( v \cdot a \):[/tex]

[tex]\[ v \cdot a = (v_x \cdot a_x) + (v_y \cdot a_y) \][/tex]

Where [tex]\( v_x \)[/tex] and [tex]\( v_y \)[/tex] are the x and y components of velocity, and [tex]\( a_x \)[/tex] and [tex]\( a_y \)[/tex] are the x and y components of acceleration. In this case, [tex]\( v_x = 0 \)[/tex] because the motion is in a circle, so [tex]\( v_y = 4.39 \, \text{m/s} \).[/tex]

[tex]\[ v \cdot a = (0 \cdot 5.00) + (4.39 \cdot (-4.00)) = 0 \, \text{m}^2/\text{s}^3 \][/tex]

Calculate the dot product [tex]\( r \cdot a \):[/tex]

[tex]\[ r \cdot a = (r_x \cdot a_x) + (r_y \cdot a_y) \][/tex]

Where [tex]\( r_x \)[/tex] and [tex]\( r_y \)[/tex] are the x and y components of the radius vector, and [tex]\( a_x \)[/tex] and [tex]\( a_y \)[/tex] are the x and y components of acceleration. In this case, [tex]\( r_x = 0 \)[/tex] because the motion is in a circle, so [tex]\( r_y = 3.00 \, \text{m} \).[/tex]

[tex]\[ r \cdot a = (0 \cdot 5.00) + (3.00 \cdot (-4.00)) = -4.00 \, \text{m}^2/\text{s}^2 \][/tex]

Complete question:

A centripetal-acceleration addict rides in uniform circular motion with period T = 4.30 s and radius r = 3.00 m. At one instant his acceleration is a = (5.00 m/s2) + (-4.00 m/s2) . At that instant, what are the following values? (a) v·a (b) r a

#1

As per work energy theorem work done by all forces must be equal to change in its kinetic energy

so correct answer will be

[tex]W_{net} [/tex] = change in kinetic energy

#2

Torque is defined as

[tex]\tau = r \times F[/tex]

[tex]\tau = rFsin\theta[/tex]

so here torque will be maximum when applied force is perpendicular to the rod

so first figure of rod is correct for maximum torque

#3

When car makes turn then its passengers moves outwards which is due to the property of inertia because due to this property passengers has tendency to move in same direction and hence it feels to move outwards

So correct answer will be

inertia

#4

As per energy conservation we can say

initial potential energy = final kinetic energy

[tex]PE = KE[/tex]

[tex]KE = mgH[/tex]

[tex]KE = 0.5(9.8)(0.5)[/tex]

[tex]KE = 2.5 J[/tex]

2. Osmosis is the process by which a solvent (water) moves through a semipermeable membrane into a solution with higher solute concentration from a solution with a lower solute concentration.

3. Diffusion is the process by which a solvent (water) moves from an area with higher concentration to an area of lower concentration.

(for one and 2 the first one is more wordy and with more scientific words but you can sub the words into either one to make it more or less wordy)

3. Animalia, Plantea, Fungi, and Protista. Protista cannot be classified as an animal, plant, or fungus.

4. Organelle, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystem, and biosphere.

5. I don't have the organelles to identify.

7. Taxonomy is the branch of science with classification, especially of organisms. Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

8. I'm not sure about the first question. Scientists name plants and animals using a system that describes the genus and species of an organism.

I did the best I could answering I really hope this helps!!

normal force is the opposite of gravity

The Normal Force is the force that acts opposite to gravity, equalizing the weight of an object resting on a horizontal surface to prevent it from falling.

In terms of basic Physics, the force that acts opposite to gravity is the Normal Force. To better understand this, imagine a book resting on a table. Here, gravity pulls the book down towards the center of the Earth, while the table exerts an upward force on the book, equivalent to the book's weight, to prevent it from falling. This upward force is known as the normal force. It's important to note, the normal force only counters gravity when the object is on a horizontal surface.

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Answer:

Option A is the correct answer.

Explanation:

 Static equilibrium means an object object is at rest and is in a state of equilibrium.

If we examine options B, C and D we can see that, in each case object is in a state of motion.

B) Tuna is in a motion.

C) Dolphin is a motion.

D) Zebra is a motion

In option A platypus lies motionless on the sand, which is an example of static equilibrium.

so, option A is the correct answer.

Answer

standing waves are created when you have a rope attached to a point By moving your hand up and down we can create waves, and as we know that our rope is attached to a point on a wall, which means it has boundary. The waves will reflect back and interface with new waves and this is how standing waves are created.

hope this will help.

Answer:

Please see the explanation

Explanation:

As we know that standing waves have nodes and anti nodes which is produced by repeated interference of two waves of same frequency in opposite direction in the same medium. In this case when we have a rope attached to a point on a wall, we move the rope in up and down direction we will create waves.

The wave will go up to the wall and then reflect back and thus create an opposite wave. And as we can create a standing wave.

There is an arrow up for air resistance and an arrow down for gravity. The arrow up is longer than the arrow down. Option a

The correct free-body diagram for a skydiver who has opened his parachute and is now slowing down as he falls would include an arrow up for air resistance and an arrow down for gravity.

Since the skydiver is slowing down, this indicates that the force of air resistance (upward force) is greater than the force of gravity (downward force), so the upward arrow should be longer than the downward arrow. This is because the skydiver is decelerating, which means the net force acting on the skydiver is in the upward direction.

When a skydiver has just opened their parachute, we see an increase in air resistance which counteracts the force of gravity. The parachute significantly increases this air resistance, and if the skydiver is slowing down, it is an indication that the air resistance force is, at that moment, greater than the force of gravity. Option a

Final answer:

The total displacement of the person's daily walk, starting and ending at the same front porch, is zero, as displacement considers only the initial and final positions.

Explanation:

The question pertains to the concept of displacement in physics, which is different from distance. Displacement is a vector quantity that only considers the initial and final position of an object, ignoring the path taken. In the case of a person who walks one mile every day for exercise, starting from her front porch at 9:00 AM and returning to the same spot at 9:25 AM, her total displacement is zero. This is because her final position (the front porch) is the same as her initial position, meaning there has been no change in position regardless of the distance walked.

friction and gravity ....................

The motion of the cake batter from the bowl to the pan is influenced by gravitational force (noncontact), normal force (contact by the spatula), and adhesive force (contact with the bowl). These forces affect how the batter moves and is transferred into the pan.

When Lourdes mixes the cake batter and transfers it from the bowl to the pan, several forces are in play affecting its motion. These include:

Each force mentioned influences the flow and transfer of the cake batter, whether it is through contact, like the normal and adhesive forces, or from a distance, such as the gravitational force.

1.

Answer:

N = 77

Explanation:

1) As we know that Tension in the wire is given as

T = 2000 N

now mass per unit length of the wire is given as

[tex]\frac{m}{L} = \frac{20 \times 10^{-3} kg}{1.5 m}[/tex]

[tex]\frac{m}{L} = 0.013 kg/m[/tex]

Now fundamental frequency is given as

[tex]f_o = \frac{1}{2L}\sqrt{\frac{T}{m/L}}[/tex]

[tex]f_o = \frac{1}{2\times 1.5}\sqrt{\frac{2000}{0.013}}[/tex]

[tex]f_o = 129 Hz[/tex]

now highest frequency is given as 10000 Hz

so total harmonics is given as

[tex]N = \frac{10000}{129}[/tex]

[tex]N = 77 [/tex]

2.

Answer:

D) 7.14 Hz

Explanation:

As we know that

speed = (frequency)(wavelength)

given that

speed = 400 m/s

wavelength = 28 m

so frequency is given as

[tex]f = \frac{400}{28}[/tex]

[tex]f = 14.3 Hz[/tex]

now if wavelength is doubled then we will have

[tex]wavelength = 56 m[/tex]

new frequency will be

[tex]f = \frac{400}{56}[/tex]

[tex]f = 7.14 hz[/tex]

3.

Answer:

Number of nodes = 4

A) 4

Explanation:

Number of nodes = number of harmonics + 1

so here we know that

number of harmonics = 3

Number of nodes = 3 + 1

Number of nodes = 4

4.

Answer:

C) 35.1 Hz

Explanation:

fundamental frequency in an organ pipe closed at one end is given as

[tex]f = \frac{v}{4L}[/tex]

here we know that

v = 345 m/s

L = 2.46 m

now we have

[tex]f = \frac{345}{4(2.46)}[/tex]

[tex]f = 35.1 Hz[/tex]

5.

Answer:

A) 570

Explanation:

Number of harmonics is given as

[tex]N = \frac{maximum :\frequency}{fundamental\: frequency}[/tex]

[tex]N = \frac{20,000}{35.1}[/tex]

[tex]N = 570[/tex]

6.

Answer:

[tex]v = 37.12 m/s[/tex]

Explanation:

For fundamental frequency we know that

[tex]f_o = \frac{v}{2L}[/tex]

here we know that

[tex]f_o = 58 Hz[/tex]

[tex]L = 32 cm[/tex]

now we have

[tex]58 = \frac{v}{2(0.32)}[/tex]

[tex]v = 37.12 m/s[/tex]

Answer:

Temperature

Explanation:

Temperature is an average measure of the kinetic energy of the object's molecules. This measure will eventually become same for two objects in a thermal contact allowing for thermal energy transfer.

To determine the amount of heat energy (Q) needed to raise the temperature of 0.90 g of copper from 9°C to 26°C, you would use the formula:

Q = mcΔT
Where:

So, Q = (0.90 g)(0.385 J/g°C)(26°C - 9°C)

By calculating the change in temperature (26°C - 9°C = 17°C) and plugging in the values, we get:
Q = (0.90)(0.385)(17)
Q = 5.8725 J

Therefore, it would take 5.8725 J of heat to raise the temperature of 0.90 g of copper from 9°C to 26°C.

b) 50 degrees

incident angle = reflected angle BUT grazing angle is given as 40 so incident angle taken from the normal at right angles to the mirror is 50

a) 40 degrees

When a light wave reflects off a mirror, it must obey the

law of reflection - angle of incidence is equal to angle of reflection.  

If the angle of incidence is 40 degrees, the angle of reflection is 40

because the form can be watched over a long time for deviations from the mark.

like fingernails, the grow slowly too. after a time, they get clipped

I think it's D)!!!!!!!!!!

I would think after watching 3 basket ball games the point gaurd.

Final answer:

The correct answer is option b as it reflects Newton's second law, stating that a constant acceleration implies a net external force. The other options misrepresent the relationship between forces, mass, acceleration, and motion.

Explanation:

The correct statement related to the motion of objects according to Newton's laws is b. An object moving with constant acceleration always has a net force acting on it. This is because Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. In other words, if there is acceleration, there must be a net force causing it.

Option a is incorrect because if an object moves at a constant velocity, there is no net force acting on it as per Newton's first law of motion. Option c is incorrect as it states a relationship between mass and acceleration that is not linear; instead, mass is inversely proportional to acceleration. Lastly, option d incorrectly describes Newton's second law; the net force on an object is equal to the mass of the object multiplied by the acceleration (Fnet = ma).

Answer:

The correct answer is 6.25 km per hour due east.

Explanation:

We are given that a horse is running due East and covers a distance of 25 kilometers in a time period of 4 hours and we are supposed to find its velocity.

The formula of velocity is similar to speed which is the ration of distance and time.

Velocity = distance / time

So putting in the given values to find the velocity of the horse:

V = 25 / 4

V = 6.25 km / hour

Answer:

The heat builds pressure

Explanation:

Consider an ideal gas in a closed system (like a gas in a container: in this case, the volume of the gas is fixed). The ideal gas equation states that:

[tex]pV=nRT[/tex]

where

p is the gas pressure

V is the gas volume

n is the number of moles of the gas

R is the gas constant

T is the gas temperature

If heat is added to the gas, its temperature T increases. n and R are constant, and V is constant as well (the container does not change its volume), so this means that the pressure of the gas, p, increases as well. The more heat is added, the more the temperature increases, the more the pressure increase: at some point, the pressure against the internal walls of the container will become so strong that the container will explode.

A. heat builds pressure.

The main goal of science is to learn about the universe and the laws of nature. (B)

The goal of Applied Science, Technology, and Engineering is to develop new inventions and processes (D), that can use the laws of nature to benefit humans. (A)

Answer:

C

Explanation:

Answer: Ultraviolet light should have a short wavelength, not a long wavelength.

Explanation:

Relation between the frequency and wavelength if given by:

[tex]\nu=\frac{c}{\lambda }[/tex]

[tex]\nu=\text{frequency of electromagnetic wave}[/tex]

[tex]\lambda =\text{wavelength of an electromagnetic wave}[/tex]

[tex]c=\text{speed of light}=3\times 10^{8} m/s[/tex]

From the above relation we can say that frequency and wavelength are inversely related to each other.

[tex]\nu\propto\frac{1}{\lambda }[/tex]

From the Gino's table, the mistake made by her was , instead of writing low wavelength for Ultraviolet rays she wrote long. Since the ultraviolet rays have higher frequency they have low value wavelength.

Answer:

option (D)

Explanation:

The elementary particles of atom are protons, neutrons and electrons. The protons and neutrons are residing in the nucleus and electron revolves around the nucleus in fixed stationary orbits.

The mass of proton and a neutron is almost same and equal to 1.67 x 10^-27 Kg.

The mass of an electron is 9.1 x 10^-31 Kg.

The mass of electron is much less than the mass of proton or a neutron.

Proton is 1837 times heavier than the electron.

Taking into account the constitution of an atom, the correct answer is option d. an electron has far less mass than either a proton or a neutron.

The smallest component of ordinary matter with the characteristics of a chemical element is an atom. Every atom consists of a nucleus in which neutrons and protons meet, and energy levels where electrons are located.

In other words, protons and neutrons constitute the atomic nucleus, the central part of the atom, whereas electrons are present in the orbitals, or peripheral region.

The neutron is an electrically neutral subatomic particle, while the proton has a positive electrical charge. Electrons have a negative charge, move around the nucleus at different energy levels and are attracted to protons, positive in the atom through electromagnetic force. The mass of an electron is almost 2000 times smaller than that of the proton and neutron.

In summary, an electron has far less mass than either a proton or a neutron.

Learn more about mass of particles of an atom:

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According to Newton's principle two

F=m*a=>a=F/m=21/82=0.25 m/s²

A 'vector' is a measurement that has a magnitude and a direction.

For the vector given here, "15 ft/s" is the magnitude, and "down" is the direction.

The magnitude of the vector described below "15 ft/s down" is 15 ft/s. The correct option is A.

A vector is the representation of a physical quantity in magnitude and direction.

For the given, "15 ft/s down" representing both the magnitude and direction.

The magnitude is 15 ft/s.

Thus, the correct option is A.

Learn more about vector.

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Answers

1. precision

2. density

3. control

4. matter

5. accuracy

6. gradation

Explanation

1. An indication of how close a measurement is to the correct result is called precision.

2. The mass of a substance per unit volume is called density of a substance.

3. A quantity in an experiment that remains unchanged or constant is called a control group.

4. Anything that has mass and occupies space is called matter.

5. The degree to which a measurement can be replicated is called accuracy.

6. Scale markings that denote equal units of measure is called gradation.

The vocabulary terms precision, density, control, matter, accuracy, and gradation match up with the definitions about measurement accuracy, mass per volume, unchanged quantities in experiments, objects with mass and volume, reproducibility of measurements, and scale markings, respectively.

The appropriate matches for the given vocabulary terms and their definitions are as follows: 1. Precision matches with 'an indication of how close a measurement is to the correct result', 2. Density corresponds to 'the mass of a substance per unit volume', 3. Control matches with 'a quantity in an experiment that remains unchanged or constant', 4.

Matter matches with 'anything that has mass and occupies space', 5. Accuracy corresponds to 'the degree to which a measurement can be replicated', and 6. Gradation fits with 'scale markings that denote equal units of measure.'

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v = speed of the source of sound or the train towards the listener or switchman = 40 m/s

V = actual speed of sound = 340 m/s

f = actual frequency of sound as emitted from source or the train = 1000 Hz

f' = frequency as observed by the listener or by switchman = ?

Using Doppler's law , frequency observed by a listener from a source moving towards it is given as

f' = V f /(V - v)

inserting the values

f' = 340 x 1000 /(340 - 40)

f' = 340 x 1000/300

The frequency of the train whistle heard by the switchman, calculated using the Doppler effect, is 380/300 x 1000 Hz.

To determine the frequency of the train whistle heard by the switchman, we use the Doppler effect formula for sound moving towards a stationary observer. Since the speed of the train is less than the speed of sound, the formula to calculate the frequency received (f') is given by f' = f ((v + v0)/(v - vs)), where f is the source frequency, v is the speed of sound, v0 is the velocity of the observer (0 m/s since the observer is stationary), and vs is the velocity of the source. Plugging in the given values, we get:

f' = 1000 Hz ((340 m/s + 0 m/s) / (340 m/s - 40 m/s)) = 1000 Hz (380 m/s / 300 m/s) = 380/300 x 1000 Hz

So, the correct frequency of the train whistle tone heard by the switchman is 380/300 x 1000 Hz.

Assume the snow is uniform, and horizontal.

Given:

coefficient of kinetic friction = 0.10 = muK

weight of sled = 48 N

weight of rider = 660 N

normal force on of sled with rider = 48+660 N = 708 N = N

Force required to maintain a uniform speed

= coefficient of kinetic friction * normal force

= muK * N

= 0.10 * 708 N

=70.8 N

Note: it takes more than 70.8 N to start the sled in motion, because static friction is in general greater than kinetic friction.