All of the following show friction as a useful force, except _____.

the heat energy produced when two surfaces rub together
having to push a rough and heavy box across the floor to move it
the friction between your feet and the floor keeping you from slipping
the tread on tires helping the moving vehicle slow down and stop when necessary

Answer:

[tex]-30m/s^{2}[/tex]

Explanation:

The first equation of motion given as,

v = u +at

Here, u is initial and v is final velocity and a is acceleration and t is time taken.

As per question car initial velocity, u = 90 m/s, final velocity, v =0 and time taken, t = 3.00 s.

Substituting these values in first equation of motion, we get

   0 = 90 m/s + a×3.00 s

or, [tex]a = \frac{-90m/s}{3.00s}[/tex]

            [tex]a=-30m/s^{2}[/tex]

Thus, the deacceleration of the car is [tex]-30m/s^{2}[/tex]

The acceleration of the car that goes from 90.0 m/s to a stop in 3.00s is -30.0 m/s².

The acceleration of the car can be calculated by using the equation:

Acceleratin = (final velocity - initial velocity) / time

= (0-90)/3

= -30.0 m/s².

Friction converts kinetic energy into heat energy as surfaces in contact oppose each other's motion, resulting in an increase in the system's thermal energy. The correct answer is: heat.

Friction changes the energy of an object from kinetic energy to heat energy. When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into heat. This conversion occurs because the force of friction acts against the motion, causing the surfaces to heat up due to the energy transfer.

Kinetic energy is the energy which a body possesses by virtue of being in motion. However, when there is kinetic friction, the irregularities on the two sliding surfaces interact to convert some of the mechanical energy into thermal energy, which is the energy stored in the motion of atoms and molecules that make up a material. The heat energy can raise the thermal energy of the system, resulting in an increase in temperature of the objects involved.

Explanation:

Given:

x₀ = 0 m

v₀ = 4.2 m/s

t = 11.6 s

a = 2.3 m/s²

Find: x

x = x₀ + v₀ t + ½ at²

x = 0 m + (4.2 m/s) (11.6 s) + ½ (2.3 m/s²) (11.6 s)²

x ≈ 203 m

Round as needed.

Answer: A.AB

Explanation:

This Velocity vs Time graph shows the acceleration of a body or object, since acceleration is the variation of velocity in time.

As we can see in the attached image, the graph can be divided in four segments:

OA: In this segment the acceleration is changing at a uniform rate. In addition we can see it has a positive slope, hence we are dealing with a positive uniform acceleration.

AB: In this segment the acceleration is changing at a nonuniform rate, since  in this part it is not possible to calculate the slope. However if this were uniform, the slope woul be positive. This means the acceleration is nonuniform and positive.

BC: In this segment the acceleration is changing at a nonuniform rate, since  in this part it is not possible to calculate the slope. However if this were uniform, the slope woul be negative. This means the acceleration is nonuniform and negative.

CD: In this segment the acceleration is changing at a uniform rate. In addition we can see it has a negative slope, hence we are dealing with a negative uniform acceleration.

From all these segments, the only one that fulfils the nonuniform positive acceleration condition is option A:

Segment AB

Answer:

AB plato users ;)

Explanation:

Answer:

The riders work becomes a combination of gravitational potential,

kinetic energy and heat.

Explanation:

His work becomes gravitational potential as the raider gains height. This can be seen from the equation of gravitational potential:

[tex]U = m*g*h[/tex],

where m is the mass, g is the gravity and h is the height. Since the rider's final position is higher than his starting position the change of gravitational position is greater than 0.

His work becomes kinetic energy as he gains speed: assuming he was at rest at starting position he must increase his speed to move to the top of the hill, and because kinetic energy depends on speed, part of his work becomes kinetic energy.

Finally, part of his work turns into heat due to all the losses because of the friction in the bicycle gears.

Answer:

4

Explanation:

Answer:

The refraction of light at the surface of water makes ponds and swimming pools appear shallower than they really are.

Explanation:

so its just the refraction of light at the surface

Answer:

The refraction of light at the surface of water makes ponds and swimming pools appear shallower than they really are. If you look at a stick that is poking into some water at an angle the stick looks bent because of refraction. The bottom of the stick seems to be nearer the surface of the water than it really is.

Explanation:

In the equation [tex]S=klnW k[/tex] represents Boltzmann constant

Answer: Option D

Explanation:

Entropy is defined as the degree of randomness of a system. In the given equation S represents entropy of the gas, k represent Boltzmann constant and W represents number of micro states possible.

W  or number of micro states means the number of ways atoms and molecules ca be arranged in a thermodynamic system. When number of micro states is more the degree of randomness namely the entropy is more.

In solid to liquid transformation the entropy increases. Similarly liquid to gas transformation also increases the entropy of the system increases.  

Answer: D.

Boltzmann's constant: 1.38 × 10⁻²³

Explanation: edmentum

Answer:

2.05×10⁶ N

Explanation:

Force = pressure × area

F = (1.52×10⁴ Pa) (135 m²)

F = 2.05×10⁶ N

The total force the bottom of the tank needs to support is calculated using the formula for pressure which is Pressure = Force / Area. By rearranging this formula to get Force = Pressure x Area, and substituting the given values, we find that the total force is 2.052 x 106 Newtons.

The subject of this question is from the field of Physics and it revolves around concepts of fluid pressure and force. The student is asked to calculate the total force exerted on the bottom of a water tank due to the pressure of the water above it. In physics, we know that pressure is defined as the force applied perpendicular to the surface of an object, per unit area. Mathematically this can be represented as Pressure = Force / Area. If we rearrange this equation to find Force, it transforms into Force = Pressure x Area.

Given in the question, the Pressure (P) is 1.52 x 10⁴ Pa and Area (A) is 135 m². Substituting these values into the equation gives us : Force = 1.52 x 104 Pa x 135 m² = 2.052 x 10⁶ N. Therefore, the bottom of the tank must support a force of 2.052 x 10⁶ Newtons.

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Explanation:

physical and chemical properties. Examples of physical properties are: color, smell, freezing point, boiling point, melting point, infra-red spectrum, attraction (paramagnetic) or repulsion (diamagnetic) to magnets, opacity, viscosity and density. There are many more examples.

For this case we must do a conversion from pounds to grams. By definition we have to:

1 pound equals 453,592 grams.

So:

[tex]3010 lb * \frac {453.592} {1} \frac {g} {lb} = 1,365,311.92\ grams[/tex]

If we divide we get the number of portions:

[tex]\frac {1,365,311.92} {28} = 48,761.14[/tex]

Thus, we have approximately 48,761 servings of sugar candy.

ANswer:

48,761 servings of sugar candy.

Final answer:

To find the number of servings, the weight of the biggest piece of fudge created (3010 lbs) was converted to grams, yielding 1,365,312.92 grams. Dividing this by the recommended serving size of 28 grams gives a total of 48,761.89 servings.

Explanation:

To calculate the number of servings in the biggest piece of fudge ever created that weighed 3010 lbs, we first need to convert the weight from pounds to grams, because the recommended serving size of fudge is given in grams (28g).

1 pound is equivalent to 453.592 grams. Therefore, we need to multiply the total weight in pounds by this conversion factor:

3010 lbs × 453.592g/lbs = 1,365,312.92 grams

Now that we have the weight of the fudge in grams, we can divide it by the recommended serving size:

1,365,312.92 grams ÷ 28 grams/serving = 48,761.89 servings

Therefore, the biggest piece of fudge ever created had 48,761.89 servings.

Answer:

The time the ball it takes to have the downward speed 4 m/s is 1.22 sec.

Explanation:

Lets explain the motion of the ball

The ball is kicked straight upwards with an initial vertical speed of 8.0 m/s

Its velocity decreases util it reaches the maximum height

At the maximum height its velocity is equal to zero

Then it fall down to the ground

We can ignore air resistance

Lets find the time it takes the ball to reach the maximum height

The acceleration of gravity is -9.8 m/s²

The initial velocity is 8 m/s upward

The final velocity is zero

So lets use the rule v = u + gt, where v is the final velocity, u is the initial

velocity, g is the acceleration of gravity and t is the time

u = 8 , v = 0 , g = -9.8

Substitute these value in the equation above

0 = 8 - 9.8 t

Add 9.8 t for both sides

9.8 t = 8

Divide both sides by 9.8

t = 40/49 seconds

The ball falls withe initial velocity zero and increases to reach 4 m/s

The velocity 4 m/s is downward

The acceleration of gravity is 9.8 m/s²

By using the same rule

u = 0 , v = 4 , g = 9.8

4 = 0 + 9.8 t

4 = 9.8 t

Divide both sides by 9.8

t = 20/49

The time the ball it takes to have the downward speed 4 m/s is the sum

of the two times above

The time the ball it takes = [tex]\frac{40}{49}+\frac{20}{49}=\frac{60}{49}=1.22[/tex] seconds

The time the ball it takes to have the downward speed 4 m/s is 1.22 sec.

Answer:

The correct answer is plastic.

Explanation:

To keep sandwiches cold as long as possible by putting them in a cooler the best material is plastic. The plastic is a thermal insulator used for different uses. One of them is to maintain the temperature in closed containers. Metal and aluminum allow the temperature to flow more easily and glass is not a suitable material for building the cooler.

Have a nice day!

Answer:

A waffle iron heated by coils

Explanation:

A waffle iron heated by coils - conduction

Food heated in a microwave oven - radiation

Pavement heated by the sun - radiation

A room heated by moving air - convection

Answer:

the mirror is 12 cm away from the image

Explanation:

Answer:

distance of image = 12 cm

Explanation:

For plane mirror the perpendicular distance of object from the mirror must be same as that of perpendicular distance of image from the mirror

As we know here that object is 3 cm high

But the distance of object from mirror is 12 cm

So here the image will be virtual and it will form at 12 cm distance behind the mirror.

So here image will form behind the mirror at same distance that is the distance of object from the mirror.

Answer:

290

Explanation:

Average acceleration is the change in velocity over change in time.

First, find the velocity by taking the derivative of position.

v(t) = dx/dt

v(t) = 38t + 21t²

At t = 3 and t = 9:

v(3) = 303

v(9) = 2043

So the average acceleration is:

a = Δv / Δt

a = (2043 − 303) / (9 − 3)

a = 290

Use appropriate units.

Answer: [tex]5 \frac{g}{cm^{3}}[/tex]

Explanation:

The density [tex]\rho[/tex] of a material is given by:

[tex]\rho=\frac{m}{V}[/tex] (1)

Where:

[tex]m=3645 g[/tex] is the mass of the cube

[tex]V[/tex] is the volume of the cube

Now, the volume of a cube is equal to the length [tex]L[/tex] of its edge to the power of 3:

[tex]V=L^{3}[/tex] (2)

If we know [tex]L=9 cm[/tex], the volume of this cube is:

[tex]V=(9 cm)^{3}=729 cm^{3}[/tex] (3)

Substituting (3) in (1):

[tex]\rho=\frac{3645 g}{729 cm^{3}}[/tex] (4)

[tex]\rho=5 \frac{g}{cm^{3}}[/tex] This is the density of the cube

Answer:

A. 45500 J

Explanation:

Internal energy of diatomic gas is:

U = 5/2 nRT

where n is the number of moles,

R is the universal gas constant,

and T is the absolute temperature.

Given n = 7.00 mol, R = 8.31 J/mol/K, and T = 40+273 = 313 K:

U = 5/2 (7.00 mol) (8.31 J/mol/K) (313 K)

U = 45500 J

Final answer:

Option C) The internal energy of 7.00 mol of N2 gas at 40°C is 8.62 × 10⁴ J, which is best approximated by option C (11,600 J) when considering significant figures.

Explanation:

The question is asking for the internal energy of a diatomic gas, specifically nitrogen gas (N2), at a certain temperature. The internal energy (U) of an ideal diatomic gas can be calculated using the formula [tex]U = (\frac{5}{2}) nRT[/tex], where 'n' is the number of moles, 'R' is the ideal gas constant, and 'T' is the temperature in Kelvin.

Firstly, convert the temperature from Celsius to Kelvin by adding 273 to the given temperature (40°C), resulting in T = 313 K. Now, use [tex]U = (\frac{5}{2}) nRT[/tex] with n = 7.00 mol, R = 8.31 J/(mol·K), and T = 313 K.

[tex]U = (\frac{5}{2}) \times 7.00 mol \times 8.31 J/(mol.K) \times 313 K = 86212.15 J[/tex]

When this value is rounded to the correct number of significant figures and expressed in scientific notation, it becomes 8.62 × 10⁴ J, which matches option C when written as 86200 J or 86.2 kJ.

Answer:

2. Understand nature

Explanation:

The main goal of science is to understand nature, because you need to find the best explanations for how nature works.

Answer:

Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms. The atoms of certain elements readily bond with other atoms to form molecules. Examples of such elements are oxygen and chlorine.

Explanation:

A molecule forms from electrons shared between two atoms. The correct option is B.

Atoms join forces and engage in interaction to create molecules. To achieve a stable electron configuration, this frequently entails sharing electrons between atoms.

Covalent bonds, a sort of chemical bond, are made possible by this sharing of electrons.

The exchange of electrons between two atoms at their outermost energy levels, or valence shells, results in covalent bonds.

Atoms can acquire a more stable structure and fill their outermost energy levels by sharing electrons, just like the noble gases do.

The atoms can achieve a lower overall energy state thanks to this electron sharing, which makes the molecule more stable than the sum of its parts.

Thus, the correct option is B.

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Answer:

16

Explanation:

the force is inverse squred proportaional to the distance

Answer:

16

Explanation:

just did it on edg

Answer:

C  1.67 × 10-9 N

Explanation:

The magnitude of the gravitational force between two objects is given by:

[tex]F=G\frac{m_1 m_2}{r^2}[/tex]

where

G is the gravitational constant

m1 ,m2 are the masses of the two objects

r is their separation

In this problem, we have:

[tex]m_1 = m_2 = 15.0 kg[/tex]

r = 3.00 m

Substituting into the equation, we find

[tex]F=(6.67\cdot 10^{-11}) \frac{(15)(15)}{3.00^2}=1.67\cdot 10^{-9} N[/tex]

The gravitational force between two 15.0 kg spheres separated by 3.00 meters is calculated to be approximately 1.67 × 10⁻⁹ N. Therefore, the correct answer is option C.

Newton's Law of Universal Gravitation:

where,

Plugging in the given values:

After simplifying:

Thus, the correct answer is C (1.67 × 10⁻⁹ N).

Answer:

Option D: 21.8 degrees

Explanation:

In a parallel RL circuit, the current in the resistor R and that in the inductor L are separated among themselves 90 degrees as illustrated in the attached image. In the image the current in the resistor is represented in orange, that of the inductor in blue, and the total current (vector addition of the previous two) is represented  in red, forming a certain angle (theta) with respect to the current in the resistor. The output voltage is the same as the input voltage as measured over the resistor R.

Therefore, the phase angle that separated output voltage and total current can be obtained using the fact that tan(phase angle) = [tex]\frac{I_l}{I_R} = \frac{x}{y} \frac{4}{10}[/tex], therefore the angle is the arctangent of 4/10:

[tex]arctang(\frac{4}{10} )= 21.801[/tex] degrees.

Answer:

The phase angle between voltage and current in a parallel [tex]RL[/tex] circuit is 21.8°

Explanation:

In this question  input voltage [tex]V_i_n[/tex]  across both the components, the resistor and inductor is same since it is  a  parallel [tex]RL[/tex] circuit.  

Current cross resistor [tex]I_R=10 mA[/tex]

Current across inductor [tex]I_L=2 mA[/tex]  

Inductive reactance [tex]X_L= \frac{ V_i_n}{I_L} = \frac{V_i_n}{(2 mA)}[/tex]

Resistance of the resistor [tex]R= \frac{V_i_n}{I_R} = \frac {V_i_n}{(10 mA)}[/tex][tex][/tex]

Phase angle between voltage and current ∅ [tex] =tan^-^1 R/X_L[/tex]

[tex]=tan^-^1 \frac{(V_i_n /10)}{(V_i_n /2)}=  tan^-^1 \ \frac{2}{10}=tan^-^1\ 0.4[/tex]

=21.8°

Answer:

Most likely the Savanna or Desert.

Explanation:

Answer:

Explanation:

Rachel and her family is most suppose to be living in a desert area.

The forest and vegetation of a desert is similar to what described location of Rachel family. The region has Cacti, short grasses and small bushes flourish.

These natural vegetation is grown in desert as they do not need much water for there growth.

Answer:

a=12

Explanation:

- add 13 to both sides

3/2a = 5+13

- multiply by 2/3

2/3 * 3/2 * a = 2/3 * 18

a = 12

Answer:

Orbit around the nucleus at specific energy levels

Explanation:

In the quantum model of the atom (Bohr's model), electrons orbit the nucleus at specific orbits corresponding to specific energy level - this means that an electron cannot be found in the space between two orbits.

Since each orbit correspond to a a precise energy level, this means that the spectrum of emission and absorption of an atom is discrete. In fact:

- When an electron jumps from a lower energy level to a higher energy level, it absorbs a photon whose energy is equal to the difference in energy between the two levels - so photons of only specific frequencies are absorbed

- When an electron jumps from a higher energy level to a lower energy level, it emits a photon whose energy is equal to the difference in energy between the two levels - so photons of only specific frequencies are emitted

Answer:

B) grams

The SI unit for mass is grams.

Answer:

The answer is grams

Explanation:

Answer:

velocity is 5m/s

Explanation:

data

d=10m

t=2sec

v=?

from

v=d/t

v=10m/2s

v=5m/s

Its SPEED is (10m/2s) = 5 m/s .

It's not possible to determine its velocity from the given information, because we don't know the direction in which it rolled.

Answer: 90 m/s

Explanation:

For this situation we will use the following equations:

[tex]y=V_{o}t+\frac{1}{2}at^{2}[/tex] (1)  

[tex]V=V_{o} + at[/tex] (2)  

Where:  

[tex]y=200 m[/tex] is the height of the model rocket at 4 s

[tex]V_{o}=10 m/s[/tex] is the initial velocity of the model rocket

[tex]V[/tex] is the velocity of the rocket at 4 s

[tex]t=4 s[/tex] is the time it takes to the model rocket to reach 200 m

[tex]a[/tex] is the constant acceleration due gravity and the rocket's thrust

Firstly, from equation (1) we have to find [tex]a[/tex]:

[tex]200 m=(10 m/s)(4 s)+\frac{1}{2}a(4 s)^{2}[/tex] (3)  

[tex]a=20 m/s^{2}[/tex] (4)  

Now we have to substitute this value of [tex]a[/tex] in (2):

[tex]V=10 m/s + (20 m/s^{2})(4 s)[/tex] (5)  

Finally:

[tex]V=90 m/s[/tex] This is the rocket's final velocity

Answer:

Weight of the suitcase, W = 220.5 N

Explanation:

It is given that,

Mass of the suitcase, m = 22.5 kg

Let W is the weight of the suitcase. The weight of an object is equal to the force acting on it due to the gravity. It is given by the product of mass and acceleration due to gravity.Mathematically, it is given by :

W = mg

[tex]W=22.5\times 9.8[/tex]

W = 220.5 N          

So, the weight of the suitcase is 220.5 N. Hence, this is the required solution.              

The weight of the suitcase is 220.5 Newton.

Given the following data:

We know that acceleration due to gravity (a) for an object is equal to 9.8 meter per seconds square.

To find how much this suitcase weigh, we would determine the weight of the suitcase by using the value of its mass.

Mathematically, the weight of an object is calculated by using the formula;

[tex]Weight = mg[/tex]

Where:

Substituting the values into the formula, we have;

[tex]Weight = 22.5[/tex] × [tex]9.8[/tex]

Weight = 220.5 Newton.

Therefore, the weight of the suitcase is 220.5 Newton.

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Segment D is -20 m/s squared

C

B

A

I know because I just did this

Segments A, B, and C can be ranked from least to greatest acceleration based on the given information.

The segments A, B, and C can be ranked from least to greatest acceleration as follows:

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