g A child bounces a 50 g super ball on the sidewalk. The velocity change of the super bowl is from 27 m/s downward to 17 m/s upward. If the contact time with the sidewalk is 1 800 s, what is the magnitude of the average force exerted on the superball by the sidewalk

Answers

Answer 1

Answer:

The average force exerted on the superball by the sidewalk is 0.00122 N.

Explanation:

Given;

mass of the super ball, m = 50 g = 0.05 kg

initial velocity of the super bowl, u = -27 m/s (assuming downward motion to be negative)

final velocity of the super bowl, u = 17 m/s (assuming upward motion to be positive)

time of motion, t = 1800 s

The average force exerted on the superball by the sidewalk is given by;

[tex]F = ma\\\\F = \frac{m(v-u)}{t} \\\\F = \frac{0.05(17-(-27))}{1800}\\\\ F = \frac{0.05(44)}{1800}\\\\F = 0.00122 \ N[/tex]

Therefore, the average force exerted on the superball by the sidewalk is 0.00122 N.


Related Questions

Six seconds after starting from rest, a car is moving at 15 m/s. What is the car's
average acceleration?
6 m/s2
0-5 m/s?
5 m/s2
2.5 m/s?
-2.5 m/s?

Answers

Answer:

  2.5 m/s²

Explanation:

a = ∆v/∆t = (15 m/s)/(6 s) = (15/6) m/s² = 2.5 m/s²

Which best explains a difference between Einstein’s general theory of relativity and his special theory of relativity?


His general theory includes uniform and accelerated motion, but his special theory applies only to uniform motion.

His general theory includes uniform and accelerated motion, but his special theory applies only to accelerated motion.

His general theory applies only to accelerated motion, but his special theory includes uniform and accelerated motion.

His general theory applies only to uniform motion, but his special theory includes uniform and accelerated motion.

Answers

Answer:

His general theory includes uniform and accelerated motion, but his special theory applies only to uniform motion.

Explanation:

According to Einstein's 1915 general theory of relativity, the force of gravity arises from the curvature of space and time.

According to theory of special relativity:

1. The laws of physics are the same for all non-accelerating observers

2. The speed of light in a vacuum was independent of the motion of all observers.

His general theory includes uniform and accelerated motion, but his special theory applies only to uniform motion.

Answer:

for those who dont like to read

the answer is A.

hope i helped

Explanation:

How do I proton and and electron compared

Answers

What’s the question?

Help me Please!!!!!!!

Answers

The speed is equal to the area under the line up to the point where t .=15 s.
Do find the area of the triangle and that if the rectangle and add them together.
The area of the triangle is 25 and the rectangle is also 25 so the speed is 50 m/s

What is the speaker’s power output if the sound intensity level is 102 dBdB at a distance of 25 mm ? Express your answer to two significant figures and include the appropriate units.

Answers

Answer:

Power  = 124.50 W

Explanation:

Given that:

The Sound intensity of a speaker output is 102 dB

and the distance r = 25 m

For the intensity of sound,

[tex]\beta (dB)= 10 \ log_{10 } (\dfrac{I}{I_o})[/tex]

where;

the threshold of hearing   [tex]I_o = 10^{-12} (W/m^2)[/tex]

[tex]\dfrac{102 }{10}= log_{10}( \dfrac{I}{10^{-12}})[/tex]

[tex]10^{10.2} = \dfrac{I}{10^{-12}}[/tex]

[tex]I = 10^{10.2} \times 10^{-12}[/tex]

I = 0.01585 W/m²

If we recall, we know remember that ;

Power = Intensity × A rea

Power = 0.01585 W/m² × 4 × 3.142 × (25 m)²

Power  = 124.50 W

A vector of components (−23, −22) is multiplied by the scalar value of −6. What is the magnitude and direction of the resultant vector?

Answers

Answer:

(1,)

Explanation:

Answer:

magnitude: 21.6; direction: 33.7°

Explanation:

A cannonball is fired horizontally from a 10 m high cliff at 20 m/s. How long will the cannonball be in the air? How far away will the cannonball strike the ground?

Answers

Answe ¡Buenos días! –

#3 ¡Buenas tardes! –

#4 ¡Bienvenid

What is the volume of an object if it has a mass of 10 grams and a density of 87 g/ml

Answers

Answer:

The answer is 0.115 mL

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{density} \\[/tex]

From the question

mass = 10 g

density = 87 g/ml

We have

[tex]volume = \frac{10}{87} \\ = 0.114942528...[/tex]

We have the final answer as

0.115 mL

Hope this helps you

A student uses a microwave oven to heat a meal. The wavelength of the radiation is 8.97 cm. What is the energy of one photon of this microwave radiation? Multiply the answer you get by 1025 to be able to input a number more easily into canvas. Enter to 2 decimal places.

Answers

Answer:

The energy of one photon is 2.21x10⁻²⁴ J. Multiplied by 10²⁵ is 22.10 J.

         

Explanation:  

The energy (E) of a photon is:

[tex] E = h\frac{c}{\lambda} [/tex]

Where:

h: is the Planck's constant = 6.62x10⁻³⁴ J.s

λ: is the wavelength of the radiation = 8.97 cm

c: is the speed of light = 3.00x10⁸ m/s

[tex] E = h\frac{c}{\lambda} = 6.62 \cdot 10^{-34} J.s\frac{3.00\cdot 10^{8} m/s}{8.97 \cdot 10^{-2} m} = 2.21 \cdot 10^{-24} J [/tex]

Hence, the energy of one photon is 2.21x10⁻²⁴ J.

Now, if we multiply the answer by 10²⁵ we have:

[tex] E = 2.21 \cdot 10^{-24} J \cdot 10^{25} = 22.10 J [/tex]

I hope it helps you!

The energy of one photon is 2.21x10⁻²⁴ J. Multiplied by 10²⁵ is 22.10 J.

Calculation of energy:

We know that

[tex]E = h\frac{c}{\lambda}[/tex]

Here

h be the Planck's constant = 6.62x10⁻³⁴ J.s

λ be the wavelength of the radiation = 8.97 cm

c be the speed of light = 3.00x10⁸ m/s

Now

Here we need to multiply the answer 10^25 so that the correct answer could come.

[tex]E = 6.62.10^{-34} \frac{3.00.10^{8}}{8.97.10^{-2}}[/tex]

=  2.21x10⁻²⁴ J.

= 22.10 J.

Hence, the energy of one photon is 2.21x10⁻²⁴ J. Multiplied by 10²⁵ is 22.10 J.

learn more about energy here; https://brainly.com/question/24719731

distance is constant and time increseas

Will Speed increase or decrease?

Answers

Answer:

The speed will be decrease

The speed will decrease

Man A (70kg) and Man B (90kg) are hanging motionless from a platform at rest. What is the tension TA in the top rope if the platform accelerates upward at a constant rate of 2 m/s2

Answers

Answer:

The tension in the upper rope (top rope), T1 = 1,888 N

Explanation:

The Parameters that were given:

Mass A, M1 = 70kg

Mass B. M2 = 90kg

acceleration, a = 2 m/s2

Assume the rope doesn't have mass, acceleration due to gravity, g

= 9.8 m/s2

The tension, T in a platform = m (a + g)

Then the tension, T1 in the upper rope = m1 (a + g) + T2

Where T2 = Tension in the lower rope

First, we calculate T2

Since the platform accelerates upward the acceleration would be positive

T2 =  m2 (a + g)

T2 = 90kg ( 2 m/s2 + 9.8 m/s2)

T2 = 1,062N

To calculate the tension T1,

T1 = m1 (a + g) + T2

= 70kg (2 m/s2 + 9.8 m/s2) + 1062N

T1 = 1,888 N

what phase changes take place when you are adding energy to the substance

Answers

Answer:

During a phase change, a substance undergoes transition to a higher energy state when heat is added, or to a lower energy state when heat is removed. Heat is added to a substance during melting and vaporization. Latent heat is released by a substance during condensation and freezing. Explanation:

A crane uses a single cable to lower a steel girder into place. The girder moves with constant speed. The cable tension does work WT and gravity does work WG. Which statement is true

Answers

Explanation:

Work done by a force is given by :

[tex]W=Fd\cos\theta[/tex]

Where

F is force, d is displacement and [tex]\theta[/tex] is the angle between F and d.

In this problem, a crane is moving in downward direction, the force gravity is in downward direction and the tension is in upward direction.

We know that if force and displacement is in same direction, work is positive while if force and displacement is in oposite direction, work is negative.

I would mean that, [tex]W_g[/tex] is positive, because gravity is parallel to the displacement and [tex]W_t[/tex] is negative, because the tension is opposite to the displacement.


A student creates an electromagnetic wave and then reverses the direction of the current. Which of the following will happen to the magnetic field?

Answers

Answer:

I believe the electromagnetic field should be reversed.

Explanation:

When a student creates an electromagnetic wave and then reverses the direction of the current, the direction of the magnetic field will be reversed.

What is an Electromagnetic wave?

An electromagnetic wave may be defined as a type of wave that is significantly created as a result of vibrations between an electric field and a magnetic field. These waves are composed of oscillating magnetic and electric fields.

According to the context of this question, when an individual is constructing an electromagnetic wave and then reverses the direction of the current, it will eventually affect the direction of the magnetic field in the same direction with respect to the current. So, if the direction of the current is reversed, the direction of the magnetic field would also be reversed.

Therefore, when a student creates an electromagnetic wave and then reverses the direction of the current, the direction of the magnetic field will be reversed.

To learn more about Magnetic fields, refer to the link:

https://brainly.com/question/14411049

#SPJ6

Your question seems incomplete. The most probable complete question is as follows:

A student creates an electromagnetic wave and then reverses the direction of the current. Which of the following will happen to the magnetic field?

The direction of the magnetic field will be reversed. The magnetic field will expand.The magnetic field would be canceled out and disappear.The magnetic field will cause the voltage of the battery to be reduced.

A bird is flying in a room with a velocity field of . Calculate the temperature change that the bird feels after 9 seconds of flight, as it flies through x

Answers

Complete Question

The complete question is shown on the first uploaded image

Answer:

The temperature change is [tex]\frac{dT}{dt} = 1.016 ^oC/m[/tex]

Explanation:

From the question we are told that

   The velocity field with which the bird is flying is  [tex]\vec V =  (u, v, w)= 0.6x + 0.2t - 1.4 \ m/s[/tex]

   The temperature of the room is  [tex]T(x, y, u) =  400 -0.4y -0.6z-0.2(5 - x)^2 \  ^o C[/tex]

    The time considered is  t =  10 \  seconds

    The  distance that the bird flew is  x  =  1 m

 Given that the bird is inside the room then the temperature of the room is equal to the temperature of the bird

Generally the change in the bird temperature with time is mathematically represented as

      [tex]\frac{dT}{dt} = -0.4 \frac{dy}{dt} -0.6\frac{dz}{dt} -0.2[2 *  (5-x)] [-\frac{dx}{dt} ][/tex]

Here the negative sign in [tex]\frac{dx}{dt}[/tex] is because of the negative sign that is attached to x in the equation

 So

       [tex]\frac{dT}{dt} = -0.4v_y  -0.6v_z -0.2[2 *  (5-x)][ -v_x][/tex]

From the given equation of velocity field

    [tex]v_x  =  0.6x[/tex]

    [tex]v_y  =  0.2t[/tex]

     [tex]v_z  =  -1.4 [/tex]

So

[tex]\frac{dT}{dt} = -0.4[0.2t]  -0.6[-1.4] -0.2[2 *  (5-x)][ -[0.6x]][/tex]    

substituting the given values of x and t

[tex]\frac{dT}{dt} = -0.4[0.2(10)]  -0.6[-1.4] -0.2[2 *  (5-1)][ -[0.61]][/tex]      

[tex]\frac{dT}{dt} = -0.8 +0.84 + 0.976[/tex]  

[tex]\frac{dT}{dt} = 1.016 ^oC/m[/tex]  

A boy whirls a ball on a string in a horizontal circle of radius 1 m. How many revolutions per minute must the ball make if its acceleration towards the center of the circle is to have the same magnitude as the acceleration due to gravity

Answers

Answer:

Nearest, the revolutions per minute will be 29.

Explanation:

Given that,

Radius of circle = 1 m

Acceleration a =g

We know that,

Angular frequency is defined as,

[tex]\omega=2\pi n[/tex]

Where, n = number of revolutions in one second

We need to calculate the revolutions in one second

Using formula of centripetal acceleration

[tex]a=\omega^2r[/tex]

Put the value of a and ω

[tex]g=(2\pi n)^2r[/tex]

[tex]n=\sqrt{\dfrac{g}{r}}\times\dfrac{1}{2\pi}[/tex]

Put the value into the formula

[tex]n=\sqrt{\dfrac{9.8}{1}}\times\dfrac{1}{2\pi}[/tex]

[tex]n=0.49[/tex]

We need to calculate the revolutions per minute

Using value for the revolutions per minute

[tex]n=0.49\times60[/tex]

[tex]n=29.4[/tex]

Hence, Nearest, the revolutions per minute will be 29.

Which factor affects the amount of runoff that occurs in an area?

land use
the water table
the saturation zone
amount of nutrients in soil

Answers

Answer:

A. land use

Explanation:

Answer:

a

Explanation:

Find the linear velocity of a point moving with uniform circular motion, if the point covers a distance s in the given amount of time t. s

Answers

Answer:

The linear velocity is represented by the following expression: [tex]v = \frac{s}{t}[/tex]

Explanation:

From Rotation Physics we know that linear velocity of a point moving with uniform circular motion is:

[tex]v = r\cdot \omega[/tex] (Eq. 1)

Where:

[tex]r[/tex] - Radius of rotation of the particle, measured in meters.

[tex]\omega[/tex] - Angular velocity, measured in radians per second.

[tex]v[/tex] - Linear velocity of the point, measured in meters per second.

But we know that angular velocity is also equal to:

[tex]\omega = \frac{\theta}{t}[/tex] (Eq. 2)

Where:

[tex]\theta[/tex] - Angular displacement, measured in radians.

[tex]t[/tex] - Time, measured in seconds.

By applying (Eq. 2) in (Eq. 1) we get that:

[tex]v = \frac{r\cdot \theta}{t}[/tex] (Eq. 3)

From Geometry we must remember that circular arc ([tex]s[/tex]), measured in meters, is represented by:

[tex]s = r\cdot \theta[/tex]

[tex]v = \frac{s}{t}[/tex]

The linear velocity is represented by the following expression: [tex]v = \frac{s}{t}[/tex]



Explain why the bottom of the ship is deeper below the surface of the sea
when the ship is fully loaded with cargo

Answers

Answer:

uhh more mass = more pull by gravity = ship go sinky more

Explanation:

7N
6
→ 2N
Net Force:
Determine the net force acting on the object.

Answers

Answer:

When a force is applied to the body, not only is the applied force acting, there are many other forces like gravitational force Fg, frictional force Ff and the normal force that balances the other force. Therefore, the net force formula is given by, FNet = Fa + Fg + Ff + FN.

Explanation:

Engineers are using computer models to study train collisions to design safer
train cars. They start by modeling an elastic collision between two train cars
traveling toward each other. Car 1 is traveling north at 20 m/s and has a mass
of 12,745 kg. Car 2 is traveling south at 15 m/s and has a mass of 4,125 kg.
After the collision, car 1 has a final velocity of 3 m/s north. What is the final
velocity of car 2?
A. 56 m/s north
B. 56 m/s south
C. 38 m/s south
D. 38 m/s north

Answers

Answer:

did you get the answer???

Answer: 38 m/s north

Explanation:

Luck walked to a store that is 250m away and it took him 50secs while Layne walked to the mall that is 1000m away and took her 200s to do. What do they have in common?

A. Average speed
B. Acceleration
C. Displacement
D.mass

Answers

Answer:

Average speed

Explanation:

250/50=5

1000/20=5

Please help me with this!

Answers

hope this helps good luck

It takes 3.8 x 10^-5 for a pulse of the radio waves from a radar to reach a plane and bounce back. How far is the plane from the radar?

Answers

Answer: 11400 m

Explanation:

Given:

t = 3.8 x 10^-5 s

v = 3 x 10^8 m/s

d = ?

Formula:

d = vt

  = (3.8 x 10^-5 s)(3 x 10^8 m/s)

  = 11400 m

hope this helps :)

The uniform movement allows to find the results for the distance from the radar to the plane is: 5.7 10³ m or 5.7 km

Kinematics studies the motion of objects looking for relationships between position, velocity and acceleration, in the special case that the acceleration is zero is called uniform motion and is described by the expression

                [tex]v = \frac{d}{t}[/tex]

                d = v t

Where v is the velocity, d the displacement and t the time.

Radar waves are electromagnetic waves with constant velocity

            v = 3 10⁸ m/s

They indicate that the time of the waves to go to the plane and return is 3.8 10⁻⁵ s, therefore if the speed is constant, the time to reach the plane is half of the total time.

          t = [tex]\frac{t_{total} }{ 2}[/tex]

          t = [tex]\frac{3.8 \ 10^{-5}}{2}[/tex]  

          t = 1.9 10⁻⁵ s

Let's calculate

        d = 3 10⁸ 1.9 10⁻⁵

        d = 5.7 10³

In conclusion with the uniform movement we can find the results for the distance from the radar to the plane is: 5.7 10³ m or 5.7 km

Learn more here: brainly.com/question/20369552

1. What quantity of heat is required to raise?

the temperature of 450 grams of water
from 35°C to 85°C?

capacity of water is 4.18 J/g °C.

Answers

Answer: Calculate the energy required in joules to raise the temperature of 450 grams of water from 15°C to 85°C? (The specific heat capacity of water is 4.18 J/g/°C)

Explanation:

The quantity of heat is required to raise the temperature of of water is 94050 joule.

What is law of conservation of energy?

Energy cannot be created or destroyed, according to the law of conservation of energy. However, it is capable of change from one form to another. An isolated system's total energy is constant regardless of the types of energy present.

The law of energy conservation is adhered to by all energy forms. The law of conservation of energy essentially says that the total energy of the system is conserved in a closed system, also known as an isolated system.

Mass of water: m = 450 grams

Initial temperature of water = 35° C

Final temperature of water = 85° C

Capacity of water is 4.18 J/g °C.

Hence, the  quantity of heat is required to raise = mass × Capacity  × raise in temperature

= 450 × 4.18 × (85 - 35) joule

= 94050 joule.

Learn more about energy here:

https://brainly.com/question/1932868

#SPJ6

How many turns are in its secondary coil, if its input voltage is 120 V and the primary coil has 210 turns

Answers

Complete Question

How many turns are in its secondary coil, if its input voltage is 120 V and the primary coil has 210 turns.

The output from the secondary coil is  12 V

Answer:

The value  is  [tex]N_s  =  21 \  turns [/tex]

Explanation:

From the equation we are told that

   The input voltage is  [tex]V_{in}  = 120 \ V[/tex]

   The number of turns of the primary coil is [tex]N_p =  210 \  turn[/tex]

    The output from the secondary is [tex]V_o =  12V[/tex]

From the transformer equation

   [tex]\frac{N_p}{V_{in}}  =\frac{N_s}{V_o}[/tex]

Here [tex]N_s[/tex] is the number of turns in the secondary coil

=> [tex]N_s  =  \frac{N_p}{V_{in}}  *  V_s[/tex]

=>[tex]N_s  =  \frac{210}{120}  *  12[/tex]

=>[tex]N_s  =  21 \  turns [/tex]

please help asap
You jog for 55 minutes and reach a park that is 4.8 km away. What was your speed?​

Answers

Answer: 59.8 or 299/5​- 55 x 4.8=264

Explanation:

Or if you wish to multiply it then the answer is above with the addition version.

Hope this helped :)

Victor has 100 trading cards, each with a distinct power level between 101 and 200 inclusive. Whenever he heads out, he always randomly selects 21 cards to bring with him just in case he meets a fellow collector. Prove that no matter which 21 cards he brings, Victor will always be able to select 4 of those cards that exhibit the following property:
Let the average power level of all 4 cards bep. The cards can be split into two pairs, each of which also has an average power level of p.

Answers

Answer:

Victor will always be able to select 4 of those cards with the following property

Explanation:

Number of trading cards = 100

victor selects 21 cards

let the 4 cards be labelled : A,B,C and D

The average power level of : A,B,C,D = ( A + B + C + D )/ 4 = P

let the two pairs be : ( A + B ) and ( C + D )

note: average power of each pair = P  and this shows that

( A + B ) = ( C + D ) for Victor to select 4 cards out of the 21 cards that exhibit the same property

we have to check out the possible choices of two cards out of 21 cards yield distinct sums.

= C(21,2)=(21x20)/2 = 210.

from the question the number of distinct sums that can be created using 101  through 200 is < 210 .

hence it is impossible to get 210 distinct sums therefore Victor will always be able to select 4 of those cards

At a certain instant, a proton is moving in the positive x direction through a magnetic field in the negative z direction. What is the direction of the magnetic force exerted on the proton

Answers

Answer: positive y direction

Explanation:

we know that direction of velocity is in +x direction

now the magnetic force is in negative z direction

therefore the magnetic force , F = q × ( v × B)

F = ( i × [ - k ] ) direction

F = j direction

so the direction of the magnetic force on the proton is positive y direction.

Name the part of the human eye which acts as a protective layer for the eye​

Answers

Answer:

Cornea

Explanation:

Cornea protects outer layer of the eye.

Other Questions
why do we get answers for free and how are we learning from this I'm mean its great but I do feel like I might regret someway later in life Mari claims that 2(to the fifth power) 3 x 5 is a multiple of a number. Is she correct? Explain. ASAP I went out to the hazel wood,Because a fire was in my head,And cut and peeled a hazel wand,And hooked a berry to a thread;And when white moths were on the wing,And moth-like stars were flickering out,I dropped the berry in a streamAnd caught a little silver trout.When I had laid it on the floorI went to blow the fire a-flame,But something rustled on the floor,And someone called me by my name:It had become a glimmering girlWith apple blossom in her hairWho called me by my name and ranAnd faded through the brightening air.Though I am old with wanderingThrough hollow lands and hilly lands,I will find out where she has gone,And kiss her lips and take her hands;And walk among long dappled grass,And pluck till time and times are done,The silver apples of the moon,The golden apples of the sun.The Song of Wandering Aengus,William Butler YeatsWrite a few sentences describing what you visualized, heard, and smelled when you imagined the poem. can someone help me use more advanced words and help me transition the sentences better. During the 1600s to 1750s worldwide exchanging networks promoted more commerce, Europeans conquered and colonized more of the Americas, the demand for African slaves to the New World increased, and global trade in tensified. In the Americas, Spain and Portugal were faced new competitors primarily England and France. With religious tensions added to the mix, the stage was set for decades of bloody warfare in Europe and the Americas. Write the rational number as a decimal -4 2/3 1. Who is the boy in the chair? *O A. a strange boyO B. the innkeepers' sisterO C. Charlie's own sonO D. Fiona's new friend 2NH.N2 + 3H2ReactantsProductOn the balanced equation above, how manyatoms of each element are in the reactant?N =H = What is the mass of 0.250 mol of chlorotrifluoromethane, CCIF3?A. 26.1 gB. 104 gC. 4.78 x 10-3 gD. 52.2g Jackie has a stack of pennies that is 0.48 inch tall. The thickness of one penny is 0.04 inch. how many pennies do Jackie have was the landing on the moon real 1. What 2 things did Admiral Penn have to do to get released from the Tower of London (jail)?need answers by 10:50 hurry SOMEBODY HELP !!!!!!! An alkali metal with fewer than 10 protons in its nucleus heyyy so like hellpppp me out Rank the three elements according to their electronegativity,from highest to lowest:Fluorine (F), Silicon (Si), Chlorine (CI) Which form of government is best?The president of your society used to be very effective he defended the nation against an attack from a foreign army, he was able to get different political parties to agree on things, and he was elected twice. But two years before the end of his term as president he messed up he was caught stealing money from the government and using it to buy houses and then sell them. Many people want him to be removed from power, but others believe that he is still a good president and deserves to finish his term, but be fined a huge amount of money as punishment for what he did. Which form of government would be the best to have in this situation? Why? how many number of subsets in set D A mug is 3/7 full. The mug contains 1/2 cup of water. Find the capacity of the mug 1 Mr. Baker calculated the area of 4 different styles of rugs. The areas of the 4 rugs are shown. OS MARULUGARES PARA P ALETICO ZORLUFERITY A = 50 m2 A5 m2 A = 2 m2 A = 15 m2 Whlch list shows the rugs in order from least area to greatest area? A Oval Rug, Square Rug, Circular Rug, Rectangular Rug B Oval Rug, Square Rug, Rectangular Rug, Circular Rug C Square Rug, Oval Rug, Rectangular Rug, Circular Rug D Circular Rug, Rectangular Rug, Square Rug, Oval Rug Pls help me!!!!!!!!!!!