An elevator is moving upward with a speed of 9.2 m/s. 3.8 seconds later, the elevator is still moving upward, but its speed has increased to 15.8 m/s. What is the average acceleration, in m/s2, of the elevator during the 3.8-s interval? Please round your answer to one decimal place.

Answers

Answer 1

From the calculations, the acceleration of the elevator is obtained as 1.5m/s^2

What is acceleration?

The term acceleration has to do with the rate of change of velocity with time.

Given that;

u =  9.2 m/s

v = 15.8 m/s

t = 3.8

a = ?

The v = u + at

a = v - u/t

a = 15 - 9.2/3.8

a = 1.5m/s^2

Learn more about acceleration:https://brainly.com/question/12550364

#SPJ1


Related Questions

A person in a hurry averages 70mph on a trip covering a distance of 500 m. what time was required to travel that distance?

Answers

The time required to travel that distance at the given speed is determined as 15.84 seconds.

Time of motion

The time of motion of the person is calculated as follows;

Distance = speed x time

time = distance/speed

where;

distance = 500 m = 0.31 mile

time = (0.31 mile)/(70 mph)

time = 0.0044 hr = 15.84 seconds

Thus, the time required to travel that distance at the given speed is determined as 15.84 seconds.

Learn more about time here: https://brainly.com/question/10428039

#SPJ1

what kind of soil is most likely found in the desert

Answers

The most likely type of soil in a dessert is sand

For thousands of years people thought that heavier objects fell faster than lighter objects. In fact, this is something that we can sometimes observe in our everyday lives. But according to Galileo this is wrong! His Law of Falling Bodies says that all objects fall at the same rate. After watching the assigned video please comment on how it is possible that Galileo's theory says one thing but our everyday experience says something else.

Answers

Answer:

See below

Explanation:

Gallileo is CORRECT in a vacuum where there is no air friction

  air friction affects same or different weight objects differently  and will cause same-weight   or different weight  objects to fall at different speeds

Andrea is investigating how increasing the concentration of sugar affects the boiling point of the solution. What would be the best way to present the results to help Andrea see if there is a pattern?

Answers

An increase in the concentration of sugar in a solution leads to the increase in boiling point of the solution.

What is boiling point?

Boiling point of a solution is that pressure exerted on a liquid by its surrounding is equal to the vapour pressure of the liquid.

When there is an increase in concentration of solute, more space will be occupied in the fluid leading to an increase in the boiling point of the fluid.

Therefore, An increase in the concentration of sugar in a solution leads to the increase in boiling point of the solution.

Learn more about boiling point here:

https://brainly.com/question/40140

#SPJ1

The area under a force-time graph represents

Answers

Answer:

Area under force time graph gives ‘impulse ‘

Which statement best defines work? (2 points) Group of answer choices
-Work is the time it takes to move an object once acted upon by a force.
-Work occurs when balanced forces act on an object and cause movement in the direction of these forces.
-Work occurs when a force causes motion of an object, and this motion is in the same direction of the applied force.
-Work is the distance over time that an object moves once acted on by a force.

Answers

Answer:last choice is correct. Work is equally to force times distance

Explanation:to generalize, W is equal to to force as a function of distance integrated over distance. Work is equivilent to energy. See work/force equivalency

the resistivity of
Copper is 1.7x10^-8ohm-m
What is the Current
density, J in the Copper
When placed inside a
Souce supply of 12v?

Answers

The current density of the copper wire is determined as (7.059 x 10⁸ A/m²)/L

Current density of the copper wire

The current density of the copper wire is calculated as follows;

J =1/ρ(E) = 1/ρ(V/L)

where;

E is electric fieldV is voltageL is length of the wireCurrent density the wire

J =1/ρ(E) = 1/ρ(V/L)

J = (1/1.7 x 10⁻⁸) x (12)/L

J = (7.059 x 10⁸ A/m²)/L

Learn more about current here: https://brainly.com/question/24858512

#SPJ1

Use the drop-down menus to complete each sentence.

The height of the cylinder is manipulated. This is the
variable.

The temperature of the water changes as the height of the cylinder changes. The temperature of the water is therefore the
variable.

A “constant” is a parameter that stays the same regardless of the variables. One parameter of the system that is held constant is the
.

Answers

One parameter of the system that is held constant that can be considered is the mass of the water.

What is a constant?

In science, the constant is a type of unmodified variable that remains equal along with the experimental procedure.

The constants of a particular system must be considered and they cannot change in experiments or observations.

In conclusion, one parameter of the system that is held constant that can be considered is the mass of the water.

Learn more about the constant of the system here:

https://brainly.com/question/17367653

#SPJ1

Which statement about bout waves is correct?

Answers

Answer:

In light waves, the electromagnetic fields oscillate perpendicular to the direction of propagation. Hence, sound waves are longitudinal waves whereas light waves are transverse waves.

Ultrasound is used to scan the unborn baby of a pregnant mother.
The detector receives an echo from the skull of the fetus 58 us after the pulse leaves the ultrasound
scanner.
Calculate the distance from the ultrasound scanner to the skull to 2 significant figures.
Give the unit for your answer.
(The speed of ultrasound in soft tissue is 1540 m/s

Answers

Explanation:

Echo method formula for speed of sound : 2 x distance / time taken

2 x distance / 58 = 1540 m/s
2 x distance = 1540 m/s / 58 s
= 26.55172414 m
Distance = 26.55172414 / 2
= 13.27586207
= 13 m

According to the law of conservation of energy, which changes would INCREASE the total energy of a system?
A. An addition of 400 J of thermal energy and a loss of 550 J of kinetic energy
B. An addition of 200 J of thermal energy and a loss of 550 J of thermal energy
C. An addition of 300 J of GPE and a loss of 450 J of thermal energy
D. An addition of 500 J of kinetic energy and a loss of 450 J of thermal energy

Answers

The changes that would increase the total energy of a system is an addition of 500 J of kinetic energy and a loss of 450 J of thermal energy.

What is conservation of energy?

The term conservation of energy means that energy can not be created nor destroyed.

In this case, the changes that would increase the total energy of a system is an addition of 500 J of kinetic energy and a loss of 450 J of thermal energy.

Learn more about conservation of energy:https://brainly.com/question/2137260

#SPJ1

Make a 1000-cm³ container. What
will be the dimensions of the
length, width, and height? How
much water will this container
hold? What is the mass of this
amount of water?

Answers

Answer:

see below

Explanation:

OK....here is one :

  L    W    H

 10 x 10 x 10  cm   =   1000 cm^2     this is a cube

    the container will hold the volume  of  1000 cm^3  of water

       which will have a mass  1 kg    ( this is a liter)

 

A car starts from rest and coasts down a hill with a constant acceleration.If it goes 90m in 8s,find the acceleration and velocity after 8s.​​​

Answers

speed or velocity= s/t => 90m/8s = 11.25 m/s => a= change in speed / change in time => 11.25 m/s / 8s = 1.4 m/s^2

Kinetic energy is energy that is stored and not moving
O True
O False

Answers

the answer to this is that it is FALSE!

A lizard climbs up a building 15.5 m and then turns around and goes down the bulding 23.7 m. This takes the lizard 31.5s. what is the average velocity of the lizard?
1.24 m/s Down
0.26 m/s Down
258 m/s Down
3.8 m/s Down

Answers

The average velocity of the lizard for the whole journey is 0.26 m/s Down.

What is average velocity?

The term average velocity has to do with the velocity of the lizard for the whole journey. We can see that the downward displacement is greater than the upward displacement.

Thus;

Velocity = displacement / time = 23.7 m - 15.5 m/31.5s = 0.26 m/s Down.

Thus, the average velocity of the lizard for the whole journey is 0.26 m/s Down.

Learn more about velocity:https://brainly.com/question/13639113

#SPJ1

What is the average translational kinetic energy of nitrogen molecules at 1600 K? A. 1.31x10-20 J. B. 2.31x10-20 J. C. 3.31x10-20 J. D. 4.31x10-20 J. ​

Answers

KE

5/2KT

For nitrogen n=5

So

5/2(1.38×10^{-23})(1600)5500×10^{-23}5.5×10^{-20}J

When the eyes are closed, what sensory organs provide such information?

Answers

Answer:

Explanation:

the inner ears and proprioreceptors

When a metal sphere is dropped in to a tall cylinder containing liquid its acceleration is g/2 (gravity over 2). Shaow that : density of metal =2density of liquid

Answers

Answer:

Fm is the net force down on the metal in air

Fm / 2 is the net force down on the metal in liquid

Fl is the buoyant force on the metal due to liquid

Fm - Fl = Fm / 2      equating upward and downward forces

Fm / 2 = Fl    

The specific gravity of the metal is twice that of the liquid

Note: F = M g = ρ V g     since ρ = M / V

Find the volume of the irregular object a marble

Answers

By using Displacement method we can find volume of irregular object like marble.

What is displacement method?

In displacement method,  

First , we measuring the volume of water displaced by an object which tell us the volume of the object.

Secondly We can use the physical balance to determine its mass.

Lastly , calculate the density by dividing the mass by the volume.

Procedure to find the Volume of irregular object i.e. marble

step 1 - Fill the graduated cylinder about half full and measure the initial volume of water.

step 2 - Drop the marble in the graduated cylinder.

step 3 -Now measure the final level of water.

Step 4 - Subtract both the values.

Here , comes the Volume of Irregular Object.

For more volume related question visit here:

https://brainly.com/question/1578538

#SPJ1

50 POINTS URGENT HELP NEEDED SPACE

Conclusion:
Your conclusion will include a summary of the lab results and an interpretation of the results. Please answer all questions in complete sentences using your own words.

Using two to three sentences, summarize what you investigated and observed in this lab.
You completed three terra forming trials. Describe the how the sun's mass affects planets in a solar system. Use data you recorded to support your conclusions.
In this simulation, the masses of the planets were all the same. Do you think if the masses of the planets were different, it would affect the results? Why or why not?
How does this simulation demonstrate the law of universal gravitation?
It is the year 2085, and the world population has grown at an alarming rate. As a space explorer, you have been sent on a terraforming mission into space. Your mission to search for a habitable planet for humans to colonize in addition to planet Earth. You found a planet you believe would be habitable, and now need to report back your findings. Describe the new planet, and why it would be perfect for maintaining human life.

DATA BELOW

sun's mass 1x—Trial One
1

5

2

3

1

1

sun's mass 1x—Trial Two
1

2

0

0

2

2

sun's mass 2x—Trial One
1

0

0

0

1

0

sun's mass 2x—Trial Two
1

3

2

0

4

0

sun's mass 3x—Trial One
1

2

0

0

2

0

sun's mass 3x—Trial Two
1

0

0

0

1

3

Answers

Answer:

Using two to three sentences, summarize what you investigated and observed in this lab. I investigated that Most of my planets and moons had the element carbon in them. I observed that Different elements absorb different wavelengths of light.

Astronomers use a wide variety of technology to explore space and the electromagnetic spectrum; why do you believe it is essential to use many types of equipment when studying space?

It is essential to use a number of telescopes sensitive to different parts of the electromagnetic spectrum to study objects in space. Even though all light is fundamentally the same thing, the way that astronomers observe light depends on the portion of the spectrum they wish to study. Tools are useful, such as detectors that help see the different wavelengths of light. Not all light can get through the Earth's atmosphere, so for some wavelengths we have to use telescopes aboard satellites.

If carbon was the most common element found in the moons and planets, what element is missing that would make them similar to Earth?  Explain why. (Hint: Think about the carbon cycle.)

The missing element that would make moons and other planets similar to earth is oxygen. The two make carbon dioxide.

We know that the electromagnetic spectrum uses wavelengths and frequencies to determine a lot about outer space. How does it help us find out the make-up of stars?  

electromagnetic radiation Explanation, astronomers observe the wavelengths by putting telescopes on mountain tops and take results of what they are seeing

Why might it be useful to determine the elements that a planet or moon is made up of?

It might be useful so we can make new discoveries of life or even plants on other planets and moons. And discover maybe even more moons one other planets.

Hope this helps!!!!

Explanation:

Question: How does a lunar eclipse occur? What evidence can you provide to explain that?

Think!!!! Write Claim, Reasoning and add evidence.

Answers

Answer:

Claim: Lunar eclipses occur when Earth passes between the Sun and the Moon, blocking the sunlight falling on it.

Evidence: A lunar eclipse is caused by Earth blocking sunlight from reaching the moon and casting a shadow across its surface. A lunar eclipse occurs when the Moon and Sun are on opposite sides of Earth. Sun-blocking Earth casts two shadows on the moon: The umbra is a full, dark shadow, and the penumbra is a partial shadow. Lunar eclipses can be divided into two types: total and partial. A total lunar eclipse occurs when the Moon and Sun are on opposite sides of Earth. A partial lunar eclipse happens when only part of Earth's shadow covers the Moon.

Reasoning:  The Moon moves into the shadow of the Earth during a lunar eclipse. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy) with Earth between the other two, which can happen only on the night of a full moon when the moon is near either lunar node.

Hope this helps you czn!!

Please Mark me Brainleast!!!!!!!!!!

Answer:

Claim: Lunar eclipses occur when Earth passes between the Sun and the Moon, blocking the sunlight falling on it.

Evidence: A lunar eclipse is caused by Earth blocking sunlight from reaching the moon and casting a shadow across its surface. A lunar eclipse occurs when the Moon and Sun are on opposite sides of Earth. Sun-blocking Earth casts two shadows on the moon: The umbra is a full, dark shadow, and the penumbra is a partial shadow. Lunar eclipses can be divided into two types: total and partial. A total lunar eclipse occurs when the Moon and Sun are on opposite sides of Earth. A partial lunar eclipse happens when only part of Earth's shadow covers the Moon.

Reasoning:  The Moon moves into the shadow of the Earth during a lunar eclipse. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy) with Earth between the other two, which can happen only on the night of a full moon when the moon is near either lunar node.

Hope this helps you czn!!

Please Mark me Brainleast!!!!!!!!!!

Calculate how many half-lives are required for a number of radio-active nuclei to decrease to one-millionth of
the initial number.

Answers

Answer:

it would depend on which element u would be considering

Explanation:

as helium , oxygen , carbon ,sodium and other would be easier while plutonium , americium and other very radioactive elements would be harder

Answer:

~ 20 half lives

Explanation:

(1/2) ^n   = 1/1,000,000     n = number of half-lives

                                        LOG both sides to get

n LOG 1/2 = -6

n = -6/(LOG (1/2)) = 19.931    or approx  20 half lives

Predict the gravitational force between two 15-kg balls whose centers are 35 m apart.

Answers

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

[tex]=\frac{(6.67\times10^{-11}N*m/kg^2)(15kg) }{(0.35m)^2}[/tex]

[tex]=1.2\times10^{-7} N[/tex]

Because the weight of one ball is mg = 147 N, the gravitational force between the two balls is [tex]1.2\times10^{-7}N[/tex] or [tex]8.4*10^3[/tex] parts per billion of the  weight.

State and prove bessel inequality​

Answers

Answer:

hope this helps and if you have any questions please feel free to ask me any time

Statement :- We assume the orthagonal sequence [tex]{{\{\phi\}}_{1}^{\infty}}[/tex] in Hilbert space, now [tex]{\forall \sf \:v\in \mathbb{V}}[/tex], the Fourier coefficients are given by:

[tex]{\quad \qquad \longrightarrow \sf a_{i}=(v,{\phi}_{i})}[/tex]

Then Bessel's inequality give us:

[tex]{\boxed{\displaystyle \bf \sum_{1}^{\infty}\vert a_{i}\vert^{2}\leqslant \Vert v\Vert^{2}}}[/tex]

Proof :- We assume the following equation is true

[tex]{\quad \qquad \longrightarrow \displaystyle \sf v_{n}=\sum_{i=1}^{n}a_{i}{\phi}_{i}}[/tex]

So that, [tex]{\bf v_n}[/tex] is projection of [tex]{\bf v}[/tex] onto the surface by the first [tex]{\bf n}[/tex] of the [tex]{\bf \phi_{i}}[/tex] . For any event, [tex]{\sf (v-v_{n})\perp v_{n}}[/tex]

Now, by Pythagoras theorem:

[tex]{:\implies \quad \sf \Vert v\Vert^{2}=\Vert v-v_{n}\Vert^{2}+\Vert v_{n}\Vert^{2}}[/tex]

[tex]{:\implies \quad \displaystyle \sf ||v||^{2}=\Vert v-v_{n}\Vert^{2}+\sum_{i=1}^{n}\vert a_{i}\vert^{2}}[/tex]

Now, we can deduce that from the above equation that;

[tex]{:\implies \quad \displaystyle \sf \sum_{i=1}^{n}\vert a_{i} \vert^{2}\leqslant \Vert v\Vert^{2}}[/tex]

For [tex]{\sf n\to \infty}[/tex], we have

[tex]{:\implies \quad \boxed{\displaystyle \bf \sum_{1}^{\infty}\vert a_{i}\vert^{2}\leqslant \Vert v\Vert^{2}}}[/tex]

Hence, Proved

why is electric current scalar quantity with having direction ?​

Answers

Explanation:

It represents the direction of flow of positive charge but is treated as a scalar quantity because current follows the laws of scalar addition and not the laws of vector addition. The angle between the wires carrying current does not affect the total current in the circuit.

Answer:

It represents the direction of flow of positive charge but it is treated as a scalar quantity because current follows the laws of scalar addition and not the laws of vector addition, because the angle between the wires carrying current does not affect the total current in the circuit.

two forces x and y are acting at 120 degrees to each other, if the magnitude are 8N and 10N respectively determine their resultant​

Answers

The resultant force of both forces is 15.62 N.

What is resultant?

The Resultant of forces is a single force obtained when two or more forces are combined.

To calculate the resultant of the force, we use the formula below.

Formula:

R = √[a²+b²-2abcos∅]..................... Equation 1

Where:

R = Resultant of the forces.∅ = Angle between both forces

From the question,

Given:

a = 8 Nb = 10 N

Substitute these values into equation 1

R = √[8²+10²-2×8×10cos120°]R = √[64+100-160cos120°]R =√ [164-160(-0.5)]R = √[164+80]R = √(244)R = 15.62 N

Hence, the resultant force of both forces is 15.62 N.

Learn more about resultant force here: https://brainly.com/question/25239010

#SPJ1

Using the parallelogram law of vectors to obtain the resultant, we have the value 16 N.

What is the resultant force?

The resultant force is that force that has the same effect in magnitude and direction as two forces acting together. In this case, we have two forces , 8 N and 10 N inclined at an angle of 120 degrees

Using the parallelogram law of vectors to obtain the resultant;

R = √([8²+10²)-2×8×10cos120°]

R = √164 +80

R = 16 N

Learn more about resultant force:https://brainly.com/question/16380983

#SPJ1

A concave mirror has a radius of curvature of 1.6m. Find the focal length

Answers

given,

Radius of curvature of concave mirror = 1.6m

We know that ,

Focal length = radius/2

Hence ,

Focal length of concave mirror = radius of concave mirror /2

=> F = 1.6/2

=> F = 0.8m

Hence the focal length of concave mirror is 0.8 m

Answer:

given,

Radius of curvature of concave mirror = 1.6m

We know that ,

Focal length = radius/2

Hence ,

Focal length of concave mirror = radius of concave mirror /2

=> F = 1.6/2

=> F = 0.8m

Hence the focal length of concave mirror is 0.8 m

Explanation:

a car travels at 50 m/s for first 20 seconds , 30 m/s for next 30 seconds and finally 20 m/s for next 10 seconds . find its average speed

Answers

The average speed traveled by car is [tex]35m/s[/tex].

[tex]1^{st}[/tex] case

Speed[tex]=50m/s\\[/tex]Time [tex]=20s[/tex]

       Distance [tex]=[/tex] [tex]speed*time= 50*20=1000m[/tex]

[tex]2^{nd}[/tex] case

Speed[tex]=30m/s[/tex]Time[tex]=30s[/tex]

       Distance[tex]=30*30=900m[/tex]

[tex]3^{rd}[/tex] case

Speed[tex]=20m/s[/tex]Time[tex]=10s[/tex]

       Distance[tex]=20*10=200m[/tex]

Now, The total distance[tex]=(1000+900+200)m=2100m[/tex]

        Total time[tex]=(20+30+10)s=60s[/tex]

       Average distance [tex]=\frac{total distance}{total time} = \frac{2100}{60}=35m/s[/tex]

To learn more about Average speed, refer to:

https://brainly.com/question/21097620

Electron grops could be considered which of the following

Answers

Answer:

Electron groups could be considered as  Lone pair electrons and bonded pairs of electrons.

Answer: Option D & B

Explanation:

The two or more electrons can be bonded by single bond, double bond, covalent bond of electrons can simply be lone pair of electrons. Unshared pair of electrons are generally termed as lone pair of electrons in an atom which are generally present in the outermost shell of atoms. Hence electron groups can be determined by bonded pairs and lone pairs of electrons.

I got this from another brainly user

If u add 1.362 and 25.2 what is the correct answer?

Answers

Answer:

26.562

Explanation:

1+25= 26

0.362+0.2= 0.562

26+0.562= 26.562

or just use a calculator

Other Questions
Find the tension in the ropes shown in the figure if the supported object weighs 600N. what is 1/10 as a decimal does it equal 0.1 Which movie couple is based on rob reiner and nora ephron?. When America entered World War II, they planned Operation Torch, aninvasion of:A. JapanOB. GermanyOC. ItalyOD. North AfricaF Jack recently took out a loan from Diane at an interest rate of 4 percent. Diane expected this years inflation rate to be 1 percent and the real interest rate to be 3 percent. The loan is due at the end of this year. Complete the table below by computing the real interest rate for each possible inflation rate. For each situation, determine whether the unexpected inflation level benefits Jack or Diane. Simplify 7x-xhow to simplify this maths question Consider this sentence from the way to rainy mountain by n. scott momaday:which two of the highlighted phrases in the passage help the reader to understand the meaning of the word deicide?the word deity means "god." the suffix -cide comes from the latin -cida, which means "kill."a)gone out of mankindb)ancient awec)there to beg and barter for an animal from the goodnight herdd)forbidden without cause the essential act of their faith(ive already done the test and got a hundred so the answers are a and d) British colonies in New Zealand and Australia differed from British colonialholdings in India because they:A. produced valuable natural resources for Great Britain.OB. broke away from British control almost immediately.OC. attracted large numbers of settlers from Great Britain.OD. granted native populations equal political rights. I need an answer. What is 485-352? PLEASE HELP ASAP WILL GIVE BRANLIEST TO CORRECT ANSWER!!What are some of the main ideas behind the Monroe Doctrine? Cite some examples from the article explaining how the Monroe Doctrine has been used in the past. The assignment for this lesson is to answer a series of questions about thecharacters in Gene Luen Yang's American Born Chinese. You'll reference the graphicnovel directly to describe how the work's complex characters develop, interact withother characters, and influence its plot and themes.You should have created a draft of this assignment in the writing activity called"Prepare Character Analysis." If you didn't complete that activity, you should go backand do so now. If you have already completed the draft, continue to the next page tostart revising. Question 14 of 43Which factor played the largest role in the African National Congress'stransition from insisting on peaceful protest to considering violence?O A. South African leaders were not tried for human rights abuses afterapartheid ended.OB. South African police opened fire on a group of citizens, killingdozens of them.OC. U.S. president Ronald Reagan refused to punish South Africa forits apartheid policies.OD. Rebel forces from Algeria took control of the South Africanindependence movement. WILL MARK BRAINLIST!!I NEED THE ANSWER STEP BY STEP.find the smallest number by which 1323 must be divided so as to get a perfect square number. Also, find the square root of the square number so obtained. Select the correct answer from the drop-down menu.Read paragraph 11 from the story.(11) At this time a rich man whom Tama's parents deemed a suitable match for their daughter presented hisproposals, and Tama was suddenly told that they approved of the marriage and that she must prepare for thebridal.What is the meaning of the word proposals as it is used in the paragraph?As used in paragraph 11, proposals means what memorial day and d day have in common? E Homework: 3.1 HomeworkEvaluate the function f(z) = 3z-8 at the indicated values.a) Find f(-4).1b) Find f2c) Find f(z-7).a) f(-4)=(Simplify your answer. Type an integer or a simplified fraction.)THINGS WILL MARK BRAINLIEST (THIS IS HARD SO 20 PTS)List a few benefits and a few limitations for each:Investigation:Experiment:InvestigationExperimentBenefits:Limitations:Benefits:Limitations: 3 benefits and 2 limitations for each, have till wednesday, so take ur time. How many starlink satellites are in orbit right now. There are ______ categories of dependent adult abuse in community-based settings. What was the name of the first Soviet satellite to travel in space? On what date was it launched?